I got a Crucial M500 960 about 6 months ago. I enabled TRIM and it was blazingly fast. I did have an occasional problem where it would reset itself in sleep mode.
However just the other week the whole system just froze up so did a restart and the Mac wouldn't boot. Luckily I had a Time Machine backup on my old hard drive in the bay where the optical drive was previously.
I had real problems trying to reformat the drive and when I did finally mange to then it started freezing again.
After some research I found that there is a known issue with SATA3 and SSD on the Mac. To top this off when I did manage to get everything back to my old hard drive back up and running the trackpad decided to die on me.
To be honest I have been looking for an excuse to justify to my wife why I need a new MacBook Pro Retina so it is kind of a good although expensive thing to happen..
So just be wary of third party SSDs. I wouldn't recommend Crucial. My Samsung SSD (SATA2) is still going strong in my 6 year old work Mac though, although work is looking to replace soon