About 8.5 hours in now. Finally decided to take a break so I can record some impressions.
1) I definitely don't mind having to roll my own party, in fact I prefer it. I feel way more attached to characters I made myself than just random people I meet along the way. Plus, this way I'm free to sculpt them as I please.
2) The equipment interface is every bit as awesome as I'd hoped. Mixing and matching equipment is given a whole new dimension thanks to being able to see all the equipment on characters. A few times I've found myself not upgrading to a higher defense because something wouldn't look good on one of my characters.
3) Dovetailing from that, the game looks great. Definitely the best graphics I've seen on the DS. Obviously it doesn't look as good as VIII, but I could easily be playing a solid PS2 game, which is quite something.
4) The only complaint I have so far is not the game's fault, but the wireless in my building isn't compatible with the DS, so I haven't been able to get online. Granted, the tag mode stuff doesn't work with wi-fi anyway, but it would be cool to at least try the shop stuff. I'll probably bring my DS to work and try it there. It's pretty clear there's a big emphasis on multiplayer stuff, but I haven't found that it detracts from the single player at all.
5) I've spent too long away (like 10 minutes, tops), I need to go back. That's how good it is.