It's a short cruise on an older ship - you just don;t get the best cruise that way but it is "what it is"
Expect smaller cabins, slightly more dated decor, fewer restaurant selections, et al. It is still NCL, so the entertainment should be pretty good, fun nightlife, tho.
Just be ready to accept it as a smaller, less spectacular cruise experience than a typical 7-day cruise. I'm sure the price is right.