SSDs are still a bit too expensive for me in general, but they are much cheaper than they used to be and they are always getting cheaper and faster.
All the studies I've read regarding modern SSDs conclude that they are as reliable as modern hard drives. They just fail differently when they do eventually fail, although typically if they fail due to the flash RAM becoming unwritable you won't lose any data, whereas with a hard drive they tend to completely die.
For me right now a 60 GB SSD is perfect, it will fit any OS installation, even Windows 7 (which enjoys taking up about 30 GB freshly installed), and then there's enough left over for the slower-loading apps. For everything else there's the standard HD, which is plenty fast enough for movies, mp3s, etc.
As far as performance, there's no question, even the original Vertex-era SSDs were hugely faster than hard drives, and there have been another two generations (or so) since. I also consider SSDs overall more reliable than hard drives, since you can drop them, throw them around, etc and they won't stop working unless you slam them with a hammer or so.. much less mere jostling/accidental droppage/slash/slash