Only reads the older 8mb PS2 Cards so if you have any of the newer 16mb cards you will have to spend some time transferring things around to get everything onto your PS3. Make sure you have an 8mb card before you start though.
Only had trouble with one saved game, which did cause me a bit of grief as I had spent a lot of time playing that particular game. Now happily playing my PS2 saved games on my PS3. Could have been a bit cheaper as only really likely to ever use it once after purchase.