My wife and I played a couple hours of this sitting on the couch with a controller, and both came out with a pretty positive feeling about the game. The humour is definitely very hit and miss, but that's just a taste thing. If you enjoy absurdist comedy, you'll probably find it more funny than not. Some of the jokes are simply referential in nature, but there's so many jokes strewn about everywhere, it doesn't feel like a significant drawback in the game, and can even surprise. There was a very deep cut to an old chat program in the second level that had us stunned for a good five seconds just saying "Wow!" over and over.
I think part of the fall off of opinion as you get further into the game might have something to do with how fresh things feel when you're first starting out, before you've had a chance to cultivate expectations about what the game does/doesn't do. That first area is just surprise after surprise as things you aren't expecting are catapulted at you repeatedly. By the time you've reached the third area, the surprises start to run out, or rather you have a better sense of what the game is trying to do.
I still think it's very enjoyable though, though an appreciation for silliness, easter eggs, or thorough snooping about is helpful in enjoying the experience.