Aion is a game that was designed to be different but has become nothing more than a generic MMO.
I believe the core game play is flawed in Aion. Even more so the basic premise of the game. There is a plethora of glitches and bugs to deal with in questing and PvE, but it's the PvP ones that really nyerk me off. Flying is one of the key things about Aion that I like. On the other hand, there are plenty of glitches and exploits to be had with flying. Dropping your wings can give the enemy player the illusion that you are falling well below but you could actually be higher than them. I'm not going to get in to this very much, mainly because I have no clue how it works or how it happens, but it happens constantly. If you are a melee class good luck getting hits on your target while flying too. Even when you are in range and they are stationary, your attacks still may not go off.
You chose to play for either Elyos or Asmodian factions. I tend to agree with the consensus of players that think the elyos have an advantage over asmos. They have better gear to drop from world bosses and their instances are easier. I have played and leveled up on both sides so this isn't just hearsay. This is the main reason for Elyos controlling the Abyss forts. I like the abyss point system in this game. The best PvP gear is bought with absurd amounts of AP but is still obtainable. It takes either a massive amount of time or very generous friends to get the AP needed to buy your endgame elite sets of PvP armor. Your faction controlling a fort is the best way for gaining AP, so Elyos have a leg up here too.
The instances are pretty decent up until the late 30's when you can no longer do Fire Temple. Getting decent gear out of them is quite common until the endgame instances. Dark Poeta (lvl 50 Instance) has been a complete waste of time for me. I've ran it about 75 times and have still never seen a gold armor piece drop for my class. Most of the gear that has dropped has been for classes that are not in our group so they have been wasted since all items are bind on pickup. The upper abyss inner instances are a great way to grind Abyss Points (which are used to buy PvP gear and consumables). The key is that your faction has to be in control of the instance to gain any benefit.
Asides from completely revamping the bland character classes, there really isn't much to be done to make this game drastically better. Aion's classes are the most standard and generic you will find on today's MMO market. The only one that brings anything new to the table is the Spirit Master. As for PvP, the person with the best gear... or the person with the biggest zerg always wins the fight.
Speaking of zergs, fort raids... Fort raids are meant to have many people involved, the game engine and servers just can't handle the numbers. Most of the time people are either too lagged out to do anything or constantly getting disconnected during fort sieges. I've had delays of up to 5 minutes for my skills to go off and I have a great internet connection and PC. It's just server lag is too much for the game when there are thousands of people in one area at one time. The side with the most players almost always wins. So pretty much all fort sieges are lopsided. Almost all servers are dominated by elyos, which leads to the fact that the factions aren't balanced. Forts are just a Zerg-fest, that's the way they were designed.
So far, the community in Aion is right on par with other MMO's out there. There are plenty of botters, gold spammers, and hackers out there. Be careful who you group with due to the fact of loot ninja's. There is no way to keep people from rolling on items only you can use in the group. Game morale is a roller coaster from what I've seen. Asmodians seem to bicker more than elyos in LFG chat but no big deal.
I'm not going to get in to how stupid the storyline is. I lost track in the late 30's and just monotonously did my campaigns to begin my Fenri's on my asmo. I don't mind grinding levels and kinah, but the grind for gear has been a huge waste of time for me. I quit pve a long time ago and only grind when I need kinah to pay for pvp or to buy Boiling Balaur Bloodstains to fail crafting my next piece of fenri's gear (4 times).
As for PvP, like I said, the people with the best gear almost always win, and the gear disparity in Aion is insane. I like Aion's PvP but constantly feel that i'm at a disadvantage due to not being able to finish my Fenri's set. I'm finished with pvp weapons and accessories, I just don't' have it in me to grind up the AP again to get the 50 Elite armor set. Furthermore, it's just not worth it. Only about half the time is a player's skill shown in pvp, rather than just their gear.
Lately, it seems that the developers are going to be the ones who put the final nail in the coffin for Aion. They made the decision to perform server merges do the the amount of people that have left since launch. Then they went a step farther by opening up free server transfers. This just made all the asmos go to the server with all the upper forts, crippling their home servers side. NCsoft has recognized their mistake and have stopped the next rounds of server transfers. Now they are left with extremely unbalanced servers and low morale among players. Who knows what bonehead mistake they will make next.
Some of Aion's high points include rifting, lvl 20-40 instances, and the feeling you get from doing well in pvp. That's about it. Since I have hit the mid 40's in leveling (November), this game has been torture.
It just isn't an enjoyable game, simple as that. The 3.5 is for all the good times I have had with friends in Aion, the game actually got a 1.