It's worth it if you need what it can do over less expensive models. Personally I hate Nikon's D3xxx series of cameras because Nikon stripped out the auto-focusing motors. This makes buying lenses more complicated and narrows your choices of AF lenses. Add in the fact that many of Nikon's lenses don't manually focus very well (e.g. any of their non pro models), this is a big deal. So, for me at least, the D5xxx series is a much better option.
On the other hand, if the D5500 CAN'T do what you want it to do, then no, it's not worth it. For example, Nikons are very bad at video. So pretty much no Nikon is worth buying if you need it for video, with the possible exception of the new D500.
All of this is predicated on you actually using the camera regularly. No camera is worth buying if it's just going to be collecting dust in a closet.