SSDs, with their finite useable life (as mentioned above, in the vicinity of 100,000 write/erase cycles per block) should really be regarded as consumable items.
HDDs have a mechanism for identifying "bad sectors" and marking these as unavailable so that future write operations do not try to write to one of these "bad sectors". SSDs use a similar approach for marking logical blocks as unavailable and many go one step further via over-provisioning (a bullshit term which should read "under-utilisation") which reserves a chunk of storage space which is "released" a logical block at a time as and when any logical block is marked unavailable. This is why you will see SSDs marked as 240GB capacity instead of 256GB as 16GB has been reserved to allow the controller to re-allocate reserve logical blocks to replace "dead" logical blocks without reducing the published capacity.
S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) was introduced to monitor the occurrence rate of a number of disk error conditions as a mechanism to help predict when a drive could be likely to fail.
SSDs also make use of S.M.A.R.T. and a number of tools are available that will allow users to interrogate the data maintained to produce a report on SSD condition. One such tool is available as a freeware download from SSD Life:
SSD Life homepage
There are a number of factors that can negatively influence the "life" of an SSD and some are rather technical but one that needs to be mentioned is the myth that "wear leveling" is beneficial. Wear leveling is achieved via re-writing data after initial write which, in fact, just increases the total number of writes and - as a result - has the effect of reducing the usable life of an SSD. Over-provisioning achieves a similar end-result without the overhead of "write amplification" (a term used to describe the ratio between writes executed versus writes required - ideally 1:1).
I'm on my third SSD (all used as system drives in a Wintel environment)...
#1 was an el cheapo 120GB SATA6G drive that occasionally used to take too long to wake up during boot and fail to be recognized resulting in boot-failures (gave it away)
#2 was an OCZ Vertex 3 120GB SATA6G drive bought to replace #1 and which worked rather well except 120GB turned out to be a bit too small (also donated - this time to a colleague building a new PC as SSD Life seemed to think it would last another 5-6 years)
#3 is another OCZ - this time their Vertex 4 in 256GB capacity and which has performed extremely well for over a year now (and SSD Life predicts another 9 years of bliss)
I've also heard horror stories about SSD failures, but most of these have been from users of low-price devices and few from users of SSDs from reputable manufacturers.
A good indicator of SSD quality is the warranty period on offer - if its 5 years, buy it!
My next SSD? If soon, will probably be OCZ's latest Vector model - as it comes with some intriguing design concepts, performs well and has a 5 year warranty.
See review at HardwareCanucks:
OCZ Vector SSD Review
Personally, I'd never revert to an HDD as a boot disk...