Tempted to use my granmothers saying "it's a bad workman who blames his tools" but let's be honest, any instrument is difficult.

The guitar is one, IMO, that is actually quite easy to learn to do something with (playing basic chords to accompany voice) but to master it - I'd guess is very hard.

I "play" a variety of instruments and am master of none. I think that a lot of this depends on where you want to be with your instrument. I do believe that there is such thing as natural ability but even those who have it probably have to work very hard to make the most of it and the rest of us (like myself) at best can only expect to acheive a reasonable degree of competence... Fun all the same.

Jon