I liked Picross ok, but only up to the 15x15 puzzles.
Any larger than that were too difficult and a pain on the DS as they were just too big to do without zooming, and the zooming was annoying.
I'm mildly intrigued by Picross 3D, but I haven't touched my DS in months. Just keep it around as it's a hinge cracked launch DS lite so it's not worth anything, and I know as soon as I ditched it they'd put out another Mario game, or a 2D Metroid or something I actually want to play.