It depends what you need. PoryZ is a very dangerous as a special sweeper, and has some very useful abilitys in trace and download. It also learns a variety of moves AND has one weakness. So why not you say? Well, although it is good, most of its plus point are done better, as it doesn't have a single niche as such, instead attempts to do everything. Want a fast special sweeper that can learn loads of moves? Why not not Landorus? Want a Pokemon that can do damage and only has one weakness? Why not Scizor?
It's hard to tell if it's worth it, since there is nothing wrong with it. But it doesn't really have any good points that can't be done with something else that good provide better synergy.
btw this I assume is in-game so I left out tiers.
Hope I helped! PX ;}