The game's simplicity is outweighed by its speed. As with the traditional Simon game, things can get overwhelming very fast. There are quite a few difficulty levels for all kinds of gamers, and the experience of drawing with a purpose on the multitouch screen does keep it interesting. OpenFeint integration means you can challenge friends for high scores, too, which increases the replayability. The one drawback I found (and maybe it's just because I was playing the game on my 1G) was that, at times, registering the strokes was wonky. I would draw it correctly, but because the game was chugging along, it would miss one of my marks or think I lifted a finger when I didn't. The recent update to the game fixes some error strokes, though, so maybe the author will smooth that out in the future.
Still, for US$0.99, White Lines is a fun touchscreen twist on the memory game, and the stark style is compelling. It's definitely worth a download, and it might even be good for keeping young ones busy while waiting in line or driving around town.