Bag space is unlimited? I'll have to try again. I'm positive it's not let me pick up an item I've not had due to the thing being full...
The text speed question I guess can't really be answered until the US version comes out, but I have to admit I've not got high hopes. It does surprise me that after some 11 editions of the game they've not thought of instant text display. It's almost criminal for an RPG...
I did say the Pokédex thing was picky, didn't I?
I just like things like that to make sense, I guess. It looks very weird to scroll through the Unown forms and see W, T, I, D, G, X, ?, R, H, A, L, E, !, K...
Edit: So I've watched a few videos and taken timings. It seems Platinum is halfway between Diamond and Ruby. But it's hard to compare because like I said, Japanese text displays faster by virtue of needing less characters. Speaking of which: Text display speed appears unaltered - JP Platinum's display seems fast because, as you've mentioned, you're used to English display speed.
Edit Again: Hm. When I saw "battles are faster", I was hoping that meant the delay after move animation (or lack of it, if you turn battle scene to off) and the slow speed at which the HP bar moves when taking damage or healing (a major gripe I hadn't mentioned earlier). The former does seem improved, the latter... the videos I've seen give me a real doubt about it >.<
Edit Again Again: Wow I seem like I'm whining. The games are good and all but it's frustrating mainly because DP made things slower and less intuitive somehow. I guess it's a sense of knowing what you're missing out on? Tell me you haven't used a Hyper Potion or Full Restore on something nearly KO'd and then sat there humming to yourself as the HP bar recovers at the pace of a stairlift.
Edit Again Again Again: Summary above HMs. But that's not much of an issue anyway.