The Platinum Standard
The game's story is actually very well done when you're up against Team Galactic. While this is an E rated game, don't think the villains won't use bombs. They do. They steal Pokemon. They take Team Rocket and basically one-up them in the bad deeds department, leading to quite an epic feel when you challenge the entire team by yourself. Other than that, the whole becoming the best trainer storyline is intact, and while it shows polish, it is pretty predictable by now.
There are an additional 60 Pokemon in Platinum's Sinnoh Dex, but this is easily balanced if you just make sure to fight every trainer, since all the trainers together will give you 203 of the Pokemon, only leaving out Dialga, Palkia, Giratina himself, Manaphy, Uxie, Mesprit, and Azelf. Almost every one of these 210 Pokemon has a different sprite than their Diamond/Pearl sprite, but I noticed certain Pokemon like Magby seem unchanged. In addition, these Pokemon and even many others in the game have new Movesets, either from switching some learned moves levels, or giving them new ones.
Now for the big pieces. Battle Frontier, while a good effort, could have had seven facilities. Where's the Battle Dome? What about the Pyramid? Most of the other facilities not found here from Emerald were trashed altogether or concepts from them led to the new ones. The five Frontier Brains are a bit more clever and mostly don't have a theme, much like the Emerald ones had (e.g. Brandon used the Regis, Tucker used familiar final evolutions, etc.). All in all, the new Battle Frontier is pretty fun, and provides a decent challenge.
The Distortion World is an awkward place, for various reasons. The most obvious is that you'll be walking along walls, surfing upside down, and other odd traveling views. However, there are no Pokemon or trainers to fight barring Cyrus and Giratina, so it feels a bit tedious inside when you have nothing to do but figure out how to run to the end. Fortunately, it's like a puzzle, so at least it's in true RPG fashion.
The Wi-Fi scene booms well here, better than Diamond/Pearl ever had done. While Friend Codes are still the norm, you have a Plaza to have fun and explore and without Friend Codes or anything else. It's basically a Trainer's Lounge. This and the Battleground, as well as the already mentioned Battle Frontier, add replay value. After all, if there wasn't constant change or new challenges to tackle, you'd have a Red/Blue clone. Yes Red/Blue are great, but after beating them, there was nothing to do but start over. Each Pokemon generation since has made some improvement to give more after-story activities to do, and Plaitnum has the largest amount of them yet.
One of the best aspects to Pokemon is the music. This game shows that Pokemon can keep up with the rest of Nintendo. While the music isn't outstanding, it's light-hearted and never feels out of the place. Major trainers like Gym Leaders, the Boss of Team Galactic have some of the most fitting music themes, leading to my final point on this aspect: the battle music is the best in the series.
The battle system, which has stuck around since 1998, still works. Unlike old level-grinds like old Final Fantasy or Dragon Quest games, Pokemon's approach to the level grind formula almost doesn't feel like level grind. And with the strategy of 17 types and 493 Pokemon to use on your opponent, battles get far from old. While it couldn't hurt to give Pokemon the ability to learn a 5th move, the restrictions and freedoms the battle system present continue to show why Pokemon is Nintendo's flagship RPG series.
With all the new, little bits of content, the large additions (Wi-Fi Plaza, Battle Frontier, etc.), and the content from Diamond/Pearl, Platinum gets you wondering what the capacity for a DS Cart is. However, with a game this addicting, you'll be more into the prospect of getting that Pokemon to Lv100 or beating the Frontier Brains.
Pokemon Platinum is hands down the best Pokemon game yet. Bravo, Game Freak. You are the masters.