I don't play all that many games with my rig, since I've been busy but most games that are not new releases will run maxed out with smooth frame rates. In Battlefield 4 on Ultra with AA off I get about 45-50 fps avg (dips to 35-40 but goes beyond 60 at times). Starcraft II wasn't very hard to 100% max out everything. Metro Last Light ran pretty good, but had serious fps drops at certain scenes in the game (10 fps drops) 35-45 avg. Tomb Raider ran like a champ maxed settings with TressFX off (advanced hair) as it usually stayed in the 50s. Not much more to say since I don't play all that many games. You can check out benchmarks out there for the card aswell.
Here's some benchmarks :
http://www.anandtech.com/show/7503/the-amd-radeon-r9-270x-270-review-feat-asus-his/5