When you say the lev el is very low, can you take a photo of the bowl at the "low" point.
It is not uncommon for the bowl to fill a little more than its "settle level" and then settle to that level. But if your bowl is draining waaaay low, then yeah, there's an issue.
Three questions before you return it: (1) Is the toilet installed level front-to-back? (2) Is it mounted back to back with any other toilets? In other words, is there another toilet directly across on the other side of the wall? Sometimes, if the toilet pipes go together into the wrong type of fixture, one can siphon the other.