I've had it for a few years. It is useful for learning and problem-solving.
Things to keep in mind: The spectrum matching feature is almost useless. The mix, the instrumentation, the key of the song, etc. can all affect the spectrum and you really can't make decisions based on seeing it on a screen and comparing it to a different song.
As an EQ (the limiter in the newest release is not too bad either) it is decent. You can make it linear or minimum phase. Having the average spectrum of the whole file displayed can be VERY useful to solve problems. Don't just go and level out all the peaks though, they may be certain transients that need to be there. You still have to listen to what you are doing or you will do more harm than good. There is a useful tool that you can use to look for peaks that are the result of comb-filtering. Surgically lowering those in the midrange can often repair a badly-recorded track.