You have to deal with it. The movie gives you nothing. Nothing at all. But it is clever. And you like it. You have to think and understand the plot. And you like it more. Sure time-travel and parallel universes are a mind-fack on their own but the movie is a little hard to follow because you start with nothing.
What would you have done if you knew that everyone around would die in 8 minutes but only you would re-spawn? Yeah I would do some weird thing too. However, couldn't the lady that hits our protagonist be a little more believable? Seriously, no matter how well you know someone, who acts like that in real life? And this supposed to be real life. This lady seriously never lost her temper! Plus she was nearly always with a smile beyond her ears! I got that out of my system. Also, I know we all want a happy ending but if your good job was on stake, you would hear your superiors and not kill the marine that spent about 3 hours chatting with him on a computer screen.
Now back to our protagonist. First of all why did he not have more questions about his body and second now that our protagonist has a new life in a new body, how will he teach a subject he has no idea about? Does he know where he lives, what he drives, where his money are and most important how big his duck is? While the credits fall, you will have lots to think and rethink. This makes it a great movie. If you understand (even a little) parallel realities and time travel you will like this movie as a whole. Acting is good (not you lady and stop smiling), the focus is also very nice through the movie and the ultimate goal achievable (with the means provided).
"Colter: Where am I? Goodwin: That's classified. Colter: Fuck you!"
"Christina: What do you want to do today? Stevens: Let's stay here for a while."