You can read negative reviews of ANY movie. By and large, I think the reviews have been very positive. It's got 8.7 stars out of 10 on IMDB right now. That's very high.
The 3 hours go by fast. The movie is great and my guess is that Leo DiCaprio is getting an Oscar nomination for his performance as Jordan Belfort.
You are right, there is always a critic with a bad review. The critic writing the review I read did a good job explaining why they thought the movie wasn't great. That doesn't mean their opinion is correct or that others wouldn't have a different opinion. It is, after all just one critic's view and as you've pointed out, other critics might feel differently.