I skipped the DSlite and upgraded to a DSi which I don't regret at all. The slightly bigger and brighter screens compared to the phat are really nice. I don't mind the lack of GBA slot either as I don't play them much anymore and I've got my phat and SP for them.
The interface is better designed and it's slighty cool that you can swap games without having to switch off as pointless as that seems.
DSiWare has provided some great games like Art Academy, Flipnote and DodoGo. I can't imagine them looking as good on the 3DS so I'd probably not import them to the 3DS and just buy 3DSware on it.
I got a phat DS on launch because it was a great price and a huge step up from the GBA. The 3DS simply isn't as big a step for me to put down twice the amount for 3D.
I've still got quite a library of unfinished games on my DS and my PS3, 360, PSP and Wii will provide more than enough entertainment. With that, I'm happy to wait a couple of years for the second 3DS model.
( Edited 25.01.2011 17:58 by Ifrit XXII )