I feel a little dirty.  I never bothered with the GBA game, I heard bad things, but I blindly picked up the original ZOE when I first got my PS2.  Terrible, terrible game.  Hated it.
A couple of weeks ago I got involved in a different ZOE2 thread, and was convinced that it was just the opposite, brilliant actually.  I'm now the proud (?) owner of all 3 ZOE games.  Haven't gotten a chance to play 2 yet, however.
In an interesting turn of events, I wound up with an extra copy of ZOE1 (+MGS2 Demo).