Well, I've played through the whole thing, so here's my insight.
The graphics are all really quite good. Much more round than previous. Yet, about the Pokemon graphics, and this pisses the hell out of me, is that they USE THE SAME BLOODY MODELS FOR POKEMON FROM THE LAST GAMES (in 3D)!!! Same movements (except when they run up to attack, but then when they reach the opponent, it's the same) for everything, except maybe a couple of tweaks. I do like it that they do run up to attack, but sometimes it turns the screen, and you don't see it physically hit the opponent, just make the attack then cut back the the attacked Pokemon. Mostly because big Pokemon attacking small ones, or land logged Pokemon attacking flying Pokemon would just look weird. There's absolutely no plot, just you going through colosseums and getting outfits. Figured there'd be such a catch when you can finally customize your trainer. And on that, most accessories are exclusive to one character. So it's like, "Oh, I like that clothing item, I'll put it on my character." but then it's only for certain characters. The thing about that, though, is that some hair colours and eye colours are exclusive to certain people! It gets really annoying, because your trainer isn't fully customizable, just what they provide. Even the colours of the clothes are absolute! I really rather like the colosseums themselves, really liked sunset colosseum altogether. Here's something I really liked: put a shiny Steelix (if you can, anyways) in Neon Colosseum, it reflects all kinds of colours all over it's body! Dunno if it happens to regular Steelix/other metal-composed Pokemon, never really tried. Another annoying thing, all of the trainers (save for Shasay, Kruger, Joe, Mysterial [more?] who have personal appearances, or avatars, if you will) are THE SAME EXACT SIX MODELS THAT EVEN YOU CAN BE!!! Thus, you're not really customed at all. I know, I'm making the game sound pretty bad, but it's not all that bad. Not to mention, the customizable phrases, and a few other things make up for it. Another point, it's only battling because it was supposed to be basically an "attachment" to Diamond and Pearl, probably because their expected popularity would make fans demand more. So yeah. my semi-rant is done.
~May update later, if anything else comes to mind.~
Can't believe I forgot the music part!
The music is OK, some is nice. Also, some little clips in the music are remixed from XD/Colosseum and only play for like 2 seconds, so they remain latent.
Reply to baratron:
Yeah, I meant that it plays the rest in my head. Also, since some people won't notice it, it would be present but hidden, as to what latent means. Sorry if it sounded bad that I said "members anyways", it's just that only members could really ask. And don't worry, attack away because you're right, I should've done that. Btw, I'll just edit out the parts that weren't exactly a good choice.