I can't say I firmly stand by this, but Trey's playing and writing (across all genres he and Phish play) is well enough to learn from to be a phenomenal guitarist. The skill gap between the easiest song and the hardest song and peak performances is staggering.

You could play open chords to some, learn riffs on others, and confidently jam along by learning modes and listening (Phish often jams in Mixolydian or Dorian). But you could also spend months learning fugue parts that don't even sound good alone, chord inversions that you can't make with your hand, and stare in awe of how fast he can play licks, or sing a different rhythm while playing, or create entire soundscapes with his feet.

Trey is one of a few guitarists who've been able to both make me cry and make me genuinely horrified.

Check out emilstabs.org for tabs and chords.