Yes, they work great for speeding up some things. However, due to their high prices, many of us are only using them for the boot drive, daw software, and plugins. We have a larger spindle drive for capturing the recorded files and session storage. But then, spindle drives are plenty fast enough for that.
Worth the cash? That is for you to decide. You won't notice any difference while tracking, but booting and program execution will be quicker. (...If your motherboard supports the higher speed interfaces such as sata III.)
What problems were you referring to?