I'm going 3/5, and here's why:
Throughout the opening with Sam, I really enjoyed the film. Hey, they even got their geeky Unix stuff right, so I give them credit for that. I liked the opening, and getting him into the grid. The Encom boardroom with Dillinger's son really setup the sequels, but hey, it provided some nice 'evil corporation' shots before Sam's big upload.
However, once he enters the grid is where the movie starts to fall apart for me, but there's three key things that made me leave the theater saddened:
ISOs - Yes, the concept of the ISOs is cool, and I knew about the subplot from the Video Game. However, in the context of the film, they made no ****ing sense. How the hell is there just randomly generated DNA in this machine from the 1980s? Okay, lets say this subplot did make sense (computer starts to process Kevin's DNA from constant leave/reentry from the portal). Only one issue with it - IT ONLY SERVED THE PURPOSE OF GETTING QUORRA IN THE REAL WORLD. It had no other plot consequences or anything else.
CLU tries to take over the world - COME ON! This is where it really did it for me. Yes, I get it - CLU created a perfect system. What's to say his trip through the portal would have even worked? Would his digital ways even work outside of the grid? I thought the only reason why Quorra could go through was her DNA-like structure...etc.
OMG SAM SHOULD HAVE JUST JUMPED IN THE PORTAL AND KILLED THE CLU PROCESS IN THE REAL WORLD SAVING KEVIN - "killall -9 clu". Instead, Kevin had to 'be the hero', and merge with CLU. At least Sam got a backup - so we can expect more Bridges in the series. (I did like the classic disc on the SIM card)
I did enjoy most of the film. These three parts really bothered me. Clearly there's no care for the computer backstory or anything anymore. That saddens me."