I am a fan of the terminator films (except for part 3 and the TV show) and I was pretty sure McG would mess this up somehow, just cuz I believed the hype, but I have to say, I enjoyed the heck out of the movie.
McG turned it out. The action set pieces were great, super fun, the tone of the movie was consistent and I really loved their winks at the original Terminator films. Script problems were sparse, but in all, it was a great popcorn flick for the summer time.
If you go in with low expectations like I did and just check your brain, I'm sure you'll have a great time.