How to summarize a game like Goat Simulator? It's a novelty. And there's not a lot left to it once the novelty runs out. At around hour 17, I got all the achievements I was ever likely to get (most of the rest were for the GoatZ DLC, and of those that weren't, two were for the nearly impossible video games inside the game), and my last three hours involved me spaced out in front of the TV, watching a show while doing flip after flip. Not what I'd call a captivating game experience.
But you know what, I think the problem lied with myself rather than any intrinsic fault in the game. I stubbornly cleaved to the idea that I was going to play Goat Simulator for 20 hours, and yet the game never promised that I'd be able to do so. It was only ever a cheap and silly thing, clearly meant for a few quick laughs and then a long residence on a back shelf.
And maybe it's okay to have limited ambitions. To want to do just one thing well instead of a hundred in a half-assed way. Maybe I should judge Goat Simulator by the standards it sets for itself, instead of the expectations I project upon it.
So, under that rubric, does Goat Simulator succeed? Is it funny enough to justify its existence? I can't say that it is. The first couple of hours were amusing, but honestly, the best thing about this game was its store page. The worlds are too small. Their borders too confining. Your character has no personality. It's a game that gives you the freedom to make your own goals and do what you want, but it doesn't feel liberating, it feels like you're being drafted to finish half the game.
I wouldn't call it a total waste of money, though. It's not worth the ten dollars they charge for it, but if you can find it on deep discount, I would not shy away from giving it a qualified recommendation. It'll make you smile. And I imagine that if you played it with friends, there's plenty of scope for competitive wackiness (in fact there were at least two multiplayer-only activities I never got to try).
I guess the worst thing you could say about Goat Simulator is that it lives up to its name. You will not be surprised by playing it, for good or for ill.