They've spent their time making Sonic as shiny as possible. Look at that Chaos 0 video IGN recently posted, that's one shiny Sonic.
Still, though, you'd think a port of a 1998 (yes, 98, I don't care when it was released in America) Dreamcast game wouldn't suffer from slowdown, but actually have a faster framerate. (Are they trying for 60 and the dips down to 30 are what people are noticing? Or are they still staying at 30 and getting the dips anyway?)
I like the idea of DX, and what they're doing looks good, but I really wish they'd spend an extra two or three months on it. There's been some DRASTIC changes between now and some of the first screenshots released just two to three months ago (and they didn't seem to even have a great deal ported over yet then), they're really cramming the work on this thing (it's like it was a back project for a couple of months, and then suddenly Sonic Team decided to focus on it and double or quadruple the staff working on it), and I'm just worried in the end it's not going to get the extra effort they intended. Videos of Windy Valley still show off awkward cameras and pop-up on a DC level, if they're still working on that, how much time are they going to have left to really add a lot of bonuses and extras? The 12 GG games and the 50-60 extra Missions are a given, but I think they had planned for a lot more and they just aren't going to have time. And a port like this doesn't usually get bumped until it's refined, it's low priority, it just gets released.
I'm going to buy it anyway, though. Even the promise of some of the extras, like new scenes and a different ending, are enough to get this Sonic fan's wallet open.