I have been buying LaCie 2.5" disks for 3 years now, and have never had any problems with them. I even bought a 500GB Rikiki last October and use it everyday, mainly for watching videos on my Xbox 360.
However, in the last week I have had to return a bad drive that died after 4 days, and the replacement for that very drive, which died after only 30 minutes! I haven't used them any differently than all my previous drives, so simply chalk it up to being a bad batch. The actual disk in both dead drives was made by Seagate (Model no. ST950032 5AS), yet all my previous LaCie's have Hitachi disks.
Basically, if you get one with a Seagate disk be sure to back up your data. I was very lucky not to lose anything that wasn't backed-up elsewhere.