The 120GB Agility is also equipped with 64MB of cache, though it's not rated at the same high speed as that of the Vertex. This should be plenty to avoid performance issues with initial use, though performance degradation will of course still occur (for a detailed explanation on SSD performance degradation, you should have a look at the relevant page of my TorqX review).
Despite being based on cheaper MLC rather than SLC technology, OCZ boasts a very high claimed mean time before failure (MTBF) rate of 1,500,000 hours. Since MLC flash modules are rated for about 10,000 write cycles before losing the ability to hold a charge, this is pretty impressive and suggests intelligent wear levelling on the part of the controller. Again, wear levelling is explained in more detail here, but it basically refers to the controller distributing data between as many flash cells as possible, minimizing multiple writes to any single cell over the SSD's lifetime.
The last though hardly least part of the equation we need to cover is TRIM, or its equivalents. If you have Windows 7 and want to get an SSD, TRIM compatibility should be high on your priority list. Without referring you back to the more detailed explanation in the TorqX review again, it basically combats SSD performance degradation, ‘cleaning' the SSD when your drive is ‘idle' (i.e. not writing). This results in files you delete actually being removed from the drive almost immediately rather than remaining behind (until the drive is filled to its maximum capacity) as ‘invalid data' to clutter and eventually considerably slow down your expensive purchase. TRIM-compatible firmware should be released for the entire OCZ range based on Indilinx controllers very soon.
If you still have Vista or XP, however, worry not. Again owners of Indilinx-based drives are lucky in that they get a tool that essentially fulfils the same function. In OCZ's case this is called the Performance Tool (equivalent to Patriot's Performance Restore Utility). The main disadvantage compared to TRIM until now was that this tool had to be user-initiated, but the new version coming out concurrently with the TRIM-enabled firmware should operate automatically whenever your SSD isn't writing, just like its counterpart.