He's the best character in the whole thing, period. I loved the whole segment when he just tells you the whole story of Cu Chulainn from his perspective, so much horrible shit is happening yet he always has that sort of "well, it is what it is" attitude through all of it, not cursing his destiny, his pacts and the betrayals that came or his existence. He really is the highlight of the whole thing. And yes, he is hilarious and has great chemistry with Taiga.
For anybody interested in Hollow Atharaxia, there is a "main plot" of sorts, but honestly, it's decent at best and just an excuse to end up in this sort of meta space where all the characters can coexist and chill. I love this sort of crap and really enjoyed for that reason the Today's Menu for the Emiya Family anime. If you really liked the characters and just want to see more of them, definitely give it a go. If you are in it for the grail lore... meh, salright