I first heard Adam Lee's covers about 2 years ago, and have been following his work ever since. When you watch the videos in chronological order, you can tell he is still improving as a player (his timing in particular, the soul was always there). He's very talented and plays with great feeling. On top of that he indeed seems to be a very nice guy too.
My favourite MJ covers by him are Smooth Criminal, Dirty Diana, IJCSLY and Human Nature. The latter is obviously inspired a bit by the John Mayer performance of the song, but I prefer Adam's version even more. It has a melancholic/mournful quality to it that gives the song a very different feel from the original.
It's a pity that he has not been uploading a lot of new work recently. Also, he has been covering several (non-MJ) pop hits that, despite the fact that he does a great job covering them, I do not really care about. Hopefully he will post a bit more of his own work in the future (he released an EP at some point), and/or more MJ covers.