The [Lego] force will be with you, always.
I am completely enthralled at present with Lego Star Wars II. Despite the number, this one deals with the original trilogy (i.e. no annoying whiney Anakin) and is an absolute blast. While one is tempted to discard it out of hand given the title (Lego? In Star Wars?) it does in fact turn out to be magic - a mix of action/platform, with 3D shoot-em-up segments, which really doesn't take itself too seriously. The only downside - the UK hasn't got the PSP version as yet, and no Mac release has been announced. Grr.
Even better, the PSP version is visually close to that of the PC version. Animation is (almost always) smooth and attractive. The game-play has enough variation to keep you interested, and with variations on the levels (play through in story mode, play through timed, play through with characters of your choice) there's quite a bit of replay value. The downsides - load times are not the best (par for the course on the PSP) and the fixed camera does mean that sometimes you can't quite see what you're doing - or where you're going, which can be painful if there's a hidden drop.
Otherwise - surprisingly fantastic, and very time consuming.