I think he's fairly easy actually (and I normally hate bosses and particularly at hard levels).
The trick for me (no cheating either) was to pick a route to run and stick to it. He will follow and once you learn his route it's just a question of being patient. Only stop to shoot when you know he will be running by blue resin.
Some of the resin roots vanish during the fight so you might need to change route a bit if they do, but I found that, even on Hard/Crushing if you keep moving and don't miss-time any jumps he will not ever damage you much even when he starts throwing grenades around. At the same time, if you are patient you will slowly but surely take him down one resin explosion at a time.
I tend to struggle with bosses, and if you try and fight him zipping around picking paths at random, etc. he is tough, but if you stick to a looping path and take your time he's actually pretty easy - that way you get the satisfaction of a Trophy without using exploits.
Try to be reasonable... its easier than you think...