Personally, I think its f*cking great. I skipped the Lite and so going from the OG DS to this one is pretty nice. The colors on the Lite always drove me nuts.
The downloadable games are great, my favorites are Box Life, Precipice and Picto Bits. Picto Bits is the shit. I love it.
If you have a creative side, Flipnote Studio is the best thing since the Gameboy Camera or the Etch a Sketch Animator. You can create cool little animations with sound. It exports them to animated .gif or even Flash via a web site. Possible the best thing about Flipnote is that its FREE!
An ExampleNote to pirates: DS/DSLite era flash cards won't work, and even the ones made for the DSi are now broke because of the 1.4 software update, so if you are into ROMs or homebrew keep your old system.
As for it not working with certain imports: I can't say that I've heard anything about this (other than the usual BS of the stores being separate from region to region). If it is true then it would be only for games released post-DSi. All my stuff works.