I'm always a bit dubious about puzzle games. They quickly get boring. However, Lumines (pronounce LOO-MIN-ESS apparently) is without a doubt the best, most addictive game I have played in a long time... no... scrub that... the most addictive game I have played ever. The simple look is just right. There are no complex fancy graphics here, just plain and simple. The sound is great with catchy tunes that, as of yet, have not started to irritate me at all. The difficulty curve is spot on. It's perfect for the portable system with short bursts or marathon length runs.
Each game starts at level 0 which at first may seem annoying, but surprisingly isn't. Eventually you will be skilled enough for games to last half an hour, an hour, who knows, but you can just put the psp into sleep mode and pick it up again later if you need to.
Puzzle mode is frustratingly addictive as well. You have to create specific shapes / patterns, but it's not always as easy as it may first look.
Anyway, buy this game. You will not be dissapointed at all.
10 out of 10