I've got a DS Lite and its a great little system. My only complain is that the Wireless/Browser capabilities of it weren't exploited more, and that it had a faster processor, more memory, higher resolution screen. That said its a great deal for $130 once you stick in an expansion cartridge (minisd card so you can store media files like videos/music/etc).
I just wish it had a few more games that looked as good as some of PSP games. Hopefully the next version of the PSP will improve upon that