I use the Song Lessons almost exclusively. How you use the site, or any educational tools is going to depend on your musical goals, of course. I just dearly love learning songs, and trying to recreate the original parts as accurately as possible. I guess part of this goes back to my days playing in a cover band, where I took great pride in playing the songs "correctly". But beyond just the satisfaction of that accomplishment, I also find that learning songs correctly is one of the best ways to improve my technique, and to learn new skills, etc. I'd far rather learn a new technique in the context of a song than as some abstract exercise. When I learn a song fully and correctly, I kind of get into another player's head, and essentially take lessons from some of the greatest players ever. 

And I can figure out songs on my own if needed. I did that for years in the cover band. I even did some professional transcribing for a while. But I found that having a good guitar teacher show you the song on video and walk through it made the learning even deeper, and often saves me from doing something in a way that's harder than it needs to be.

I've occasionally looked at some of the other lesson content, but honestly, if all of that material disappeared tomorrow and we were left with only the Song Lessons, I wouldn't bat an eye.