It really depends on the theatre and the work. For example, the boxes in the Winter Garden are awful because the theatre is so wide to begin with. Yet I have liked my box seats at the Hirschfeld and Sondheim.
Boxes in theatres with small casts are generally good, but not musicals with a lot of dancing.
Finally, make sure they are on the outer side of the box, not the entrance. I once sat in a box for a big hit and had to stand for most of the show because the people in front of me were tall.
Finally, when I was young, I would frequently leave my really cheap seats and sit in a box for the second act. It was generally fun to be so close, but the perspective was frequently skewed, especially with a large cast.