Bleh.
£229 is a fair chunk of change for a start, and certainly a long way off the current pricing of the DSi. I for one would certainly wait for some deep price cuts, but knowing Nintendo that's unlikely to happen any time this year. I can't see parents being willing to drop that much coin as well - I reckon DSi sales will continue to be strong.
Second, it looks old. The design hasn't changed since the DS, bar a few tweaks, yet other hardware looks sleek and slim in comparison - even the PSPgo! Nintendo have to realise they're competing with Apple as well, and Apple know how to make things small and look good too. It looks fat, pocket-unfriendly and not modern.
Personally, 3D is rubbish - but that's due to my own eyesight. Hearing multiple reports that it only works from one very narrow angle? Not so good - but I'll reserve judgement until the public gets hands on them.
Finally, the battery life. Oh my days. Are we regressing here? 3.5 - 5 hours? Is that it? My iPad far outdoes that...
Things I'd make better:
1) Modern casing, not a boring box
2) Battery life
3) Cost
4) Region lock
5) Capacitive touch and ditch the stylus