Just seen it and I pretty much agree on everything already said. MAJOR SPOILERS FOLLOW!
Jake absolutely killed it and reminded me a lot of a performance I bring up a lot, namely Eric Roberts in Star 80. They play very similar characters, broke sociopaths in who seem determined to make it big in flashy LA by any means necessary and both actors show tremendous commitment to their part. What helps Jake a lot here though is the dialogue, that isn't afraid to embrace how insane its main character is, and how casually it is displayed. Every scene where Lou negotiates is brilliant in the way it shows us how his logic works, with the centerpiece being the dinner date where he essentially forces Nina to have sex with him. It's so seedy and pulpy that it works in darkly comical way, despite being utterly creepy at its core. Then there's the small touches that add so much to the character with so little. Think of the scene where he sprays cleaner on his shirt and then irons it while watching an old comedy movie or tv show where a knight is beheaded. He looks around to see if anyone else caught that (of course not, he's alone in his apartment) and then lets out a loud laugh as if it was the funniest thing he ever saw. It tells us everything we need to know about this guy and luckily the movie refrains from telling us much more.
The ending didn't quite work for me either, it was not only abrupt but I thought it missed a climax for his character, or to quote himself, a 'critical moment' for the character. I think Gilroy intended that moment to be when Lou let his assistant get shot and film his death, but while extreme I don't think it was anything beyond what we already expected him to be capable of at that point. It would've helped if the detectives investigating him actually got something on him that would also give the moment of him getting away with it all more impact. Now it really felt like he just breezed through everything, it was all a bit too easy. Also, all the satirical subtext got a bit too heavy handed and obvious as well.
Nevertheless, this will end up really high on my year end list, and I'd like to give a couple more quick shoutouts.
I too died whenever Bill Paxton would say "breh" and died at how over the top he emphasized that one "Brah!". That man is just too perfect for parts like these.
Even though it was probably luck, the best shot in the movie I saw was when Lou punched the mirror and it shattered, but one big shard still hung sideways in the frame so it showed Lou's reflection perfectly.
If it wasn't for the trailer spoiling it, the final line of the movie would've been one of the greatest final lines I've ever heard. I'm sure in time it will get properly acknowledged for being a perfect final line though.
No confiscation of his hard drive? Analysis of his search history?
Nonsense.
Total departure from everything we'd seen from her and their relationship
from the beginning and very concerned with her success and Jake was on the bummy side in the early times. When he excelled at his job, she was more attracted to him. 
Made enough sense to me.
oh let me guess you are one of those ones, "there was no plot it was just a character study" 
Prisoner's was my favorite movie of last year, largely in part to his acting in that flick. He nailed it again (was good in Enemy also I just disliked that entire movie by the time it was done.)
