Yeah, Trace Memory is one of my favorites. It really took advantage of the DS's features to create awesome puzzles. ^_^
My only problem with it was that it was really short. I think it only took me five hours to beat, if that. But it's an awesome game nonetheless and I recommend it to everyone.
If you like Trace Memory, you NEED to check out Hotel Dusk Room 215. It's by the same people that did Trace Memory and it's just as good. It's also a lot longer.