Hi Loner,
I've been on Remeron several times with great success, my pdoc prescribed it to treat anxiety and depression. The side effect profile is very different from most other ADs.
Sedation and weight gain are the two biggies, though I never experienced the weight gain myself. The sedation, though, seems to be extreme in most cases, myself included - at first it literally knocked me out cold for 12 hours, and the hangover was horrible. HOWEVER, it really does get better within a few days. From what I've read, a lot of people get so freaked out after that first dose that they drop it altogether without giving their bodies a chance to adjust to the med. My pdoc warned me about this, so I knew what to expect; the hangover feeling stopped after 3 days and, although it still knocked me cold within 45 minutes of taking it, I was able to straighten out my sleep patterns with no trouble (using a very loud alarm clock

)
The good news: if you stick to it, it usually works great. Remeron also works quickly (usually within 10 days), it improves sleep architecture (deep, refreshing sleep), it's a great add-on if you're taking SSRIs such as Zoloft (it might cancel out some SSRI induced side effects), and it's also been shown to improve alcohol and drug sobriety rates. My mood literally skyrockets whenever I take it.
BTW, I stopped taking it several times back in my drinking days so I could pick up the booze again. :wtf2
So that's my experience. YMMV of course, I hear that some people don't experience the extreme sedation. Some people need to adjust their eating habits to deal with the weight gain. If you decide to try it, make sure you start taking it whenever you can afford to sleep in for a couple of days (weekend etc). Hope this helps!
Matt