I saw this tonight and I enjoyed it immensely. I literally was laughing from the first minute all the way to the end. Full disclosure: I loved Ghostbusters 1 and 2 growing up but also have really enjoyed Paul Feig's comedies so the humor is absolutely right up my alley.
Kate McKinnon stole the freakin' show, but seriously all the leads added something to the film. I'd say all the weakest parts were in the trailer but there are laughs in what was expanded upon in these scenes. I didn't even mind the villain, even though I had heard he was a real weak point from a majority of criticisms before.
The only part that's slightly conflicting is what keeps the movie from being even better is the fan service worked in. The cameos are fun but do take you out of the movie. It would have been a hard sell without some of them (imagine marketing with no Stay Puft or Slimer), but I think there's a better movie in there without them.
I'm honestly surprised it found such a stride it's first go-around with the chemistry, humor, and GHOSTS, and a sequel could be even better. This was truly a Ghostbusters movie through and through and that's all I could have asked for. Also, this will look FANTASTIC on Blu-ray.
I would give it 4/5.