Closer to 4.5 stars. I read this to my 13 year old son, and he agrees. We're starting the sequel tonight! 
 I liked this one a lot, everything about it. The premise consists of a geeky computer hacker finding the file that governs pretty much everything. By adjusting variables in the file, he can alter his physical location, his cell phone battery life, and the balance on his bank account. This last part leads to some trouble with the law, so our hero teleports himself to medieval England, where he finds lots of company. 
 The book boasts plenty of nerd and pop culture references, laugh out loud moments, and sarcastic, biting barbs. I also rolled my eyes quite a bit, but in an entertained way, not in the 'oh this is SO STUPID' way. I could've used another female character, but having only one (not counting that, er, lady in the tavern) doesn't detract from the story. 
 A fun and easy read, highly recommended for geeks, nerds, gamers, and any combination of them.