I have one that I used until a few weeks ago when I got a 970. I could play most games on high settings at 720p and get 40+ fps, including Crysis 3 and Watch Dogs. At 1080p most games tanked into the 30s on high settings, even older games like unmodded Skyrim.
So if you have a 720p monitor and are OK with 40 FPS, you probably will be fine for most games.
That said, I think the 750 ti is probably still a better value - it's a pretty significant performance increase for just 20-30 dollars more.