I think SSD's are like bigger carburators, for a motorcycle, there are small setbacks at different "things" say, if you add two more carbs, "RAID 0" lower RPM throttle response "disk writing of small files" is down a bit, but overall, engine power at the higher rpm range is better than ever "read speed of any file size and I/O performance".
This comes at the expense of FUEL and the added power, usually decreases the life of the motor... Err, SSD's are high maintenece if you don't already know about that stuff; there are things you need in order to preserve the write speed, and get the most out of the solid state drives expected life, "wiper/trim/secure erase and partition starting offset/allignment etc.." Since those aren't built into older drive controllers "on the motherboard", and older opperating systems don't support some of those, preserving the write speed on the SSD is pretty high maintenance, basically, you never want to write on/erase/rewrite, you only want to put something on there that you will use daily, without changing that daily used thing. If you change files alot/write/rewrite/erase etc.. The drives tend to get slower and slower, to an extent.. To get that back with older hardware, some of the drives need to be completely reflashed to factory spec, destructive type SSD bios version flashing, where everything is reset to zero's, sort of like HDD low level formatting..
I am trying to use them mostly for MY stuff, rather than background opperating system functions.. I got the OS/SYSTEM drive to be much like a ROM; with as little drive writes as possible to the SSD array, and all of my other OS random/system drive writes moved over to an outside track partition, of a pair of mechanical drives, RAID 0.. Things that I prefer to use the SSD's for are like videogame small files, with few to no updates/patches to those games.. to get the most read speed and lowest "access/latency" for better game play, less jumpy/gittery ingame graphics, and less loading time between maps/tracks etc..
Performance wise, the SSD's are MUCH faster than mechanical disks.... Windows load times are faster, program load times are faster.. etc.. need to open a photo, click boom it's open at full resolution, then final dithering/rendering "Canon DPP software loads big photos from CD/DVD and mechanical disks much slower than the SSD..
Need to open all of your applications at once, use a batch file.. see how long it takes on a regular Hard disk, then compare it to the same setup using an SSD..
If you are able to view video's on youtube, there are a few really good examples of just how fast things are with SSD's. It was a needed improvement in PC's, regarding Data bottlenecking that standard hard disks have. We still need a bit more speed, newer SSD's and SATA channels are coming out that should make things alot faster than they are now.