It's pretty common for critics to be more critical than the average moviegoing public. The Mummy currently has a 16% approval rating on RT.com which is very low. The audience approval score is at 44% which is higher, but so what? It's still awful. Compare this to Baywatch which has a 19% approval rating from critics and 63% from audiences. Or Pirates which got a 29% from critics and 68% from audiences. For the audience score to be higher on a would-be blockbuster is in no way unusual. These kinds of movies almost always get better ratings from audiences than critics.
As for Cruise, he's got some years left in him. But like all movie stars, he's fading. In the 90's, if Tom Cruise had starred in a big budget popcorn movie like this, it would have crushed at the box office. In fairness, there isn't an actor working today with the box office draw Cruise had in the 80's and 90's. The Mission: Impossible franchise and international box office will keep Cruise afloat for a while to come. I have seen some writers who seemed to take some pleasure in Cruise's latest misstep (they did the same thing when Knight & Day disappointed in 2010) but I haven't seen anything I would describe as "viscous".
As for The Mummy, I haven't seen it. Based on everything I have seen, I have no desire to. But I don't have a dog in this fight either. I'm just looking at the numbers as objectively as one possibly can. They suggest that overall, critics and audiences strongly disliked the movie.