I've played loads of UL and have a good understanding of pretty much every aspect. I can't be bothered to write it all down here (maybe in my club forum) but if anyone wants a game I'll be happy to go a few rounds and explain it over a game.
My best advice is don't be a complete *** and quitter like a lot of apparently 'Legend' and even 'TL' tier players I've encountered who quit because they can't handle the ego bruising after getting a few shots wrong. If you don't succeed try again and have fun with it.
Don't just learn to play the fairway, learn the difficult lies. There's a lot to consider and remember.
What I like about UL is it requires more judgement and consideration for each shot, much more like the real thing. There's also a lot more can go wrong which can also be a positive as it teaches players to learn how to play recovery shots.
EL can become fairly mundane and predictable after playing X amount of rounds over and over on the same courses. It then just becomes about who can hit the ding more (and make less mistakes on meter) than the other. Whereas in UL the lie really affects the shot so there's more possibilities which brings a lot more to the game.
A lot of players of all tiers don't like it basically because they suck at it because it is a lot harder. Unfortunately if you have that loser mentality you're not going to enjoy it but if you have the patience to learn and master UL it becomes more and more enjoyable.
I will add UL is a more complicated thought process and is really for the advanced player. I would recommend that all players try it but that all player gets to grips with EL first before going into UL. Once you have a handle on EL you're ready to try UL.
Unfortunately many players on WGT just play lots of rounds and fabricate conditions to drop their average and claim a tier which doesn't reflect their ability.
The true sign of a good player and one that actually deserves to be called a 'Legend' or 'Tour Legend' etc is a player that can show consistency in both EL and UL in ANY conditions.