Many excellent improvements to DotA, yet just falls short of superb.
Heroes of Newerth - HoN for short - is based on the popular Warcraft 3 mod Defense of the Ancients (DotA). A multiplayer-only 5v5 game, your aim is to kill a particular structure in the other team's base. This structure is defended by an increasingly powerful set of towers as well as constantly-spawning NPCs called "creeps". Against this, you control an avatar which gains levels and gold as the game progresses. With your teammates, you have to push down towers, farm gold for ever-more-powerful items and annihilate the other team when they try to stop you.
Simple enough in theory, but in practice HoN is a tough game. There are over 70 heroes to choose from, each with four skills. Although some heroes' skills are similar, others are completely unique. Dangerously, if you aren't at least borderline familiar with every single one of these heroes, your performance suffers. Those who do not know for example that the hero Scout can go invisible at will may find themselves assassinated by him one too many times. Not knowing that Aluna has a stun may result in channeling spells interrupted before doing much damage; not knowing that Predator can go magic-immune for a short while may short-circuit a player's plan to disable Predator with spells and flee. These are all deadly mistakes that can be swiftly punished - a hero who's getting focused can be killed in less than 2 seconds, and bad positioning can easily mean your death. The learning curve is such that if you're new, you will be mercilessly massacred and dissected, respawn after respawn, game after game.
In some games, dying is a drawback, but not too big of one. Your team simply fights for a while one man down, and then you rejoin the fray intact and whole as before. The other team has a short-term numerical advantage, but afterwards the playing field is level once again. This isn't the case in HoN. Other players gain a lot of experience and gold each time they kill you, and this effect quickly snowballs. The result is that it's generally better to play a 4v5 game than to play a 5v5 if one of your teammates is new.
This tough environment makes HoN a difficult game to get into, and the anti-newbie tension is legendary. Since you can lose a game because just one of your allies are bad, and since each game lasts upwards of 40 minutes, you have a long time to suffer! Frustration quickly mounts, players get yelled at, egos clash, people ragequit. Shucks. There's unfortunately nothing much that can be done about this learning curve other than to stick with it. For those who persevere however, a good game of HoN is immensely rewarding and is, without exaggeration, one of the best experiences in the gaming world.
In DotA, finding these good games can be difficult. So-called "public games" - games which anyone can join - are notorious because you have no idea how good the other players are, and can result in a complete stomp. Arranged games on the other hand tend to take a while to organize. Compared to DotA, HoN has it much better. Each player is assigned a rating that starts at 1500 and evolves as the player wins or loses matches. There's also an "autobalance" button that reshuffles players to have equal rating on both teams. This makes it easy to estimate another player's skill, and to play decent games. Every now and then you still get a gross skill mismatch, but in general the games are fairly balanced.
Game-wise, HoN is almost a clone of DotA. Several heroes are directly imported from DotA, with more or less the same skills and stats. The similarity is such that HoN is immediately familiar to any seasoned DotA player, although enough differences exist too that you cannot immediately hop from one game to the other. Being a far newer game, HoN also exhibits numerous technical improvements. The graphics are much superior, and there are complex hero skills that DotA do not have. Excellent improvements not possible with the DotA engine for example include being able to see a hero's mana in addition to health easier, as well as being able to see how many seconds are left on a particular effect (say, an invisibility rune).
HoN also brings together lots of other nice touches as well. One great improvement is auto hotkeys, whereby all heroes use q, w, e and r to use their skills. This lessens the learning curve slightly because there's no need to memorize a new set of keys for every hero. Using items is much easier as well; everything can be activated with alt + q, w, e and r. During hero selection, you can indicate which hero you intend to pick, helping everyone form a balanced lineup, and an in-built voice chat system helps with coordinating the team. Buying items is easier, and there is a "recommended" tab as well for your hero. Players can vote to concede, to remake (in the event of a player not loading for example) or to kick players from the game, all features unavailable in DotA. There's also a leaver-tracking system such that although a player can leave games, they will be tracked and eventually cannot join no-leaver games. This means leavers in HoN are far fewer than in DotA.
If HoN improves in every aspect over DotA (which is itself a superb game), why do I only rate it 8.5? To be honest, it's difficult to explain. When you play HoN, you win some and you lose some. When you win by a crushing margin however, you don't get much fun or satisfaction (unless in some demented way your "fun" is derived in stomping players much worse than you, in which case you are contributing to the newbie-hostile environment of HoN). Neither is it fun or satisfying to lose by a crushing margin, especially since you'll probably get taunted or raged at in the process. Even relatively balanced games can be unsatisfying. When one team is significantly better than the other, the game often becomes a slow but inexorable slide to that side winning, such that when they finally win, neither team feel they've really enjoyed the match. These games are still fun, but uplifting, deeply rewarding fun they are not. HoN is only really satisfying when you play an evenly poised match where both sides have chances deep into late-game – and these kind of games are few and far between.
The much-criticized community is another real problem with the game. Although as one gains skill at the game the community also gets more accommodating, it's still possible for players to aggravate one another. This happens mostly as a consequence of HoN's voting system. It's possible also for a team member to not concede even when there's no chance left of winning, just to annoy (this tends to happen when there's an argument over who's playing badly). Everyone else cannot leave the game because it racks up their leaver percentage, yet kicking the offending player out is often impossible since a kick vote requires "yes" from the other team as well (something they're not likely to give). As a result, the game gets frustrating quickly.
A particularly evil case is that of the "spy". The idea is to have two accounts, and put them on different teams. Once the game starts, the griefer intentionally dies with the spy account again and again, increasing his main account's kill-death ratio as well as essentially guaranteeing a victory. The victims cannot concede because the spy votes to continue the game, they cannot leave because it racks up their leaver percentage and finally they cannot kick the offending spy from the game because the griefers will vote no. This leaves a very bitter taste as the victims are forced to endure ~40 minutes of the griefers farming kills. Fortunately at least, HoN has an in-built report system that will (hopefully) get all the griefers banned.
Finally, it is worth noting that HoN is not available for South East Asian players because of a partnership between S2games and Garena. SEA players can play the game, but only on Garena servers. This means SEA players cannot play on international servers or vice versa, and cuts SEA players from the world. This is a massive drawback of HoN, because it means that online friendships formed via other games cannot be carried over to HoN if one party lives in South East Asia.
If one is willing to look over HoN's high learning curve and fractious community, HoN makes a great game to play. The sheer exhilaration of being in a good HoN game is something very few other games can match, and the game is updated fairly often so the game stays refreshingly new. For those unwilling to put up with the community's constant nagging, flaming and lambasting however, it might be wiser to give Heroes of Newerth a miss.
Pros: occasional sterling games lead to blood-pumping, fist-shaking thrills; many varied heroes and items, leading to high complexity; popular enough to make getting games easy; plenty of small improvements over the base game, DotA; frequently updated.
Cons: high learning curve, often-hostile community with a significant number of griefers, high learning curve, South-East-Asia restricted, high learning curve.