Depends on the era. Lots of his stuff is relatively easy to play, but it's stuff I'd never think to write. His approach to the guitar from a creative perspective is where his strength lies.
What do you mean by your last sentence?
And why do you say it is stuff you'd never think to write? Especially you???
From a purely technical perspective, Alex isn't anything to write home about. He's basically just a blues-rock guitarist as far as technique goes, but the reason he sounds so very different from, say, Stevie Ray Vaughan (who was a tremendously talented guitarist) is because he comes up with different ways of skinning cats. He's the master of making one guitar sound like more than one guitar. Playing in that style isn't hard, but coming up with that approach was genius.
I'm a decent player -- somewhat edgy and emotive -- but I lack the ability to come up with truly inspired guitar parts.
She was probably hearing qualities that only she, as a player, could hear.
As an intermediate saxophonist (I'm considered very good by my peers, but I'm only in high school, and I can' to lay much college level stuff) I agree completely with your musical family members. You can practice and practice till you get the notes without a doubt, you can learn every scale and mode and memorize them backwards, forwards, and otherwards, you can have an insane level of talent and learn to make sounds that boggle the minds of most anyone you show them to, but without emotion, passion, and true deep musical feeling, your work has little chance of making an impact.