The 480 is faster, in many cases almost as fast as a Fury X, but worth the upgrade? No. If you are at 1440p and games you play tend to be VRAM heavy it would be worth it after selling your 290. If you aren't selling then I'm not sure it's worth it..
AMD should be releasing a RX400 series refresh, dubbed RX500 that should be using a better manufacturing process to get more OC, could be worth the wait if you want to stay AMD. They are also releasing Vega very soon as well, which would be a big big jump in performance for anything AMD, with that said I'd say wait on the upgrade and save up and upgrade your CPU as well tbh. It will limit what you can do and if you jump up in GPU performance you won't be getting as much as you could.Upgrade to say Ryzen 5 if budget is tight would be a pretty big upgrade and you'd be set for years once again