Is it overrated? I don't know. I like it a lot and its success apparently saved the film series from death. It was a huge critical success in comparison to TMP, which is probably where half the reputation comes from.
It brought Trek back to the mainstream. Trek films had tried to top it for years. Even X-Men 2 aped the ending. It also allowed its characters to evolve and grow over the course of the story. The Kirk at the start of TWOK is not the same guy at the end. Ot was a way of saying "these people are moving forward." I didn't get that feeling in the TMP films.
Overrated? I don't think so, but who cares? It's all opinion anyway. There is never going to be a consensus. As always, everyone's mileage varies.