A well implemented 5.1 surround can offer a fantastic experience ... but it really comes down to what you are trying to recreate. The promise of ATMOS (and other like formats) is to place objects in 3d space independent from the system and room that it is being recreated in.

Now that said, I can't tell you if it can live up to this promise as I've never really heard well implemented ATMOS content on a well implemented ATMOS system. Rich