Players who want to get "good" need to really focus on their technique. Thumb behind the back of the neck.......use all four fingers on the fretboard. Myself, I have been playing guitar since I was 14 years old(I am 36 now). I am far from a virtuoso like Ursin DeRoche but I consider myself an above average(good) player.
Due to family and work(that thing people do to earn money to pay bills) commitments for the longest time I stopped playing guitar. Pretty much from the ages of 14 to 16, I worked solidly at playing guitar and I became a good player. I was fortunate to have a good guitar tutors when I was younger to teach me the correct way to do things.
You have to spend ALOT of time to get fluent in the more advanced techniques of the instrument(Alternate picking etc). This is true......if you don't practice constantly your picking technique will go to pieces in a very short matter of time.
With Legato and pull off technique this isn't the case from my own experience. About 4 years ago, I suffered a paralysis type injury in my right arm. Not a serious one and I have somewhat recovered from it but it has effected my picking technique. I have stiffness and muscle cramps my right arm now.