Happy birthday has an alright opening, and has a nice setup to have a weird drug-fueled psychedelic adventure. Drug Shaman Steven Tyler makes an appearance along with a couple shady characters and they do some cool camera effects and words on the screen.
They almost immediately turn it into a kidnap & torture movie and only have one hallucination scene. At that point the movie is alright, but different. It's not particularly good, but it does have some uncomfortable scenes, which seems like the main point they wanted to stick.
The ending(s) they decide to use are awful, like truly absolutely awful. They felt lazy, and unbelievable in every way and really killed the whole film for me. That said, it wasn't an awful watch, and it held my attention for a lot of it. It wasn't a total train wreck, but the ending is bad enough that I'd skip this for something better.
Some of the ending scenes are done well on their own, but the story is just so-so-so bad at that point, so it was tough to appreciate them. I think it could have been an easy 6 with a better story and probably much higher if they committed to the "Fear and Loathing In Las Vegas" feel they initially setup.
Drug Shaman Steven Tyler also turned out to be a pretty lame character, which is a shame since he is pretty great in the first scenes.
