In the "performance" category speed has almost doubled in two years, both lower mem. writes and reads and higher mem. writes and reads. Same size's (though more offerings) and less money, and with a 2 year perspective about half the price. (..for commercial SSD's.)
There are two exceptions with performance:
1. is a sandforce based SSD and "incompressible" data.
sandforce controllers compress data for improved performance and extended write-life, BUT some things just aren't going to be compressed.
Under non-compressible conditions they "fall-back" to about half of their performance, which is about the same as max performance 2 years ago.
2. -older, and just slightly older drives (..and it's particular SSD models), will drop performance once a certain amount of writes are performed. Some of the newer drives however don't seem to have this problem - including the newer sandforce variety. It's usually not quite the "halving" of performance as seen in #1, but it can get that bad with some SSD's.
Basically the better new performance SSD's are at the limits of the controller now (for Sata 3) at least with respect to higher mem.. The older drives were doing the same thing to Sata 2 (though some probably exceeded sata 2 with higher mem., but couldn't provide it because of the Sata 2 bus).
SSD's with their lower price drops are starting to "take-over" sales though. Laptops/Pads in particular, but also for PC enthusiasts.
An OS only SSD isn't a bad idea for an enthusiast - and it can hit that less than $100 dollar price-point. I've personally got several Plextor M5S's at 128 gig which is more than enough for the OS and the added space for extras, plus space for increased longevity - purchased on sale for about $80 each.
Comparison with Hard Drives (on a Sata 3 to Sata 3 basis): http://www.legitreviews.com/article/1907/3/
Note: it's those little non-sequential reads and writes that are particularly important once the OS is loaded and being used. Look at how much those values change for the better with the inferior 300 gig Velociraptor + the Crucial caching drive (top light-blue bar on the Crystal Disk Mark graph at the bottom of the web page). (..real-world with reads though it will require those files to be cached on the Crucial caching drive - which could take some time to do depending on how often the files are accessed.)