You're likely to hear a lot of criticism for this show, and with good reason: People often become frustrated when faced with things they don't understand -- and it certainly doesn't help that the show is purposely abrasive, with unlikeable characters, a million sight gags/puns/lines hitting you a second, and the worst "art style" imaginable.
However, the abrasiveness is part of the humor, and that's PFFR's whole thing (look at Wonder Showzen or some of their music): Alienate people as quickly as possible so you can leave the people truly for looking beyond the surface to find brilliant, unique art. And with Xavier, what you have is a show not for the masses at all -- and certainly not for the typical Adult Swim set. This is a total work of GENIUS, and I don't throw that word around very often.
Surreal, bizarre, seemingly-100% nonsensical at times... but so, SO unbelievably consistently hilarious, intelligent, and clever. Have you seen a television show lately that you could describe as "mindblowing"? Probably not. Well, this is your show. It's probably way too intelligent for the average Adult Swim viewer... hell, it's probably way too intelligent even for the people who enjoy the show! There's ALWAYS some new line to pick up on. I've watched some episodes 10 times and still catch new things. It's hard to describe in detail how absolutely INSANE this show is!
But if you're the typical Adult Swim fan, you may want to pass on this one... however, if you're into the films of Lynch, Giuseppe Andrews, Jodorowsky, etc. or the music of The Residents, Harry Partch, Captain Beefheart... you know, the truly bizarre and "outside" part of the entertainment world... you will most likely love this exploration of existentialism and absurdity. This show is probably the most insanely and violently brilliant thing on television. Ever. So unbelievably packed with sight gags and clever quips, an 11 minute episode has more energy and ideas than entire seasons of pretty much every other show you can think of.
Never have I seen an animated series explore these themes. It attempts so much with what little it has. It's not random at all... one little line has layers and layers of depth. I'll admit it's probably a bit hard to take at first (as any truly groundbreaking art is), but remember that it's just a show that makes fun of the dangers of spirituality. With that in mind, you should be able to see the beauty. Personally, I think this is without question the most brilliant thing I've seen in forever, and I've fallen so hard in love for it that it's ridiculous. I've actually TURNED ON MY TELEVISION lately, just to watch this show. Will most people like it? Probably not. But if you want something truly unlike anything you've ever seen, get this immediately.