For me, the Agility 3 120GB I received had firmware 2.06 applied. I had continual freezes and BSOD (0x0000007A or 0x000000F4) on my new build.
I updated the firmware to 2.11 and things have much improved but I still experienced the odd completely random BSOD. I have taken the SSD out and used a mechanical HDD and can't replicate the fault at all.
According to OCZ, who admit the fault affects 3% of units, possible causes I've read range from Intel's RST or the Sandforce firmware through to the BIOS or the Sandybridge chipset itself or a combination of each.
I've not had a single issue with the SSD for around 10 days now but with the issues I've encountered, my confidence in the reliability of SSD's in general isn't that high now.