i've used sony, ricoh, pioneer, plextor, lg, lite-on, and samsung (in THAT exact order) and my FAVORITE was plextor, and SECOND was the samsung.
Considering the fact that the CHEAPEST plextor i owned cost $160, and the samsung only cost me $39, i'd say i'm fairly IMPRESSED with the samsung. It's the SATA 18x model. There's already a replacement for it that's 20x, but i haven't had any experience with that drive.
It does a very good job, and is very imparticular about discs. My LG was good, but very fussy. It would burn badly on bad media, and good on good media. The plextor would burn PERFECTLY on everything, but cost $160+ and only lasted me 1-2 years. The samsung, however, was affordable, and does a pretty good job, regardless of the quality of media used (although never as good as the plextor, keep in mind)
I've been happy with them, tho. They're 183's