Pros: Fast, factory overclocked, runs very cool, extremely quiet, ShadowPlay
My first impressions were very positive. The card just looks cool. I could care less about this, but I know that to some enthusiasts how it looks in the case is important. On that score this card does very well with it's sleek design and gold tones. It also comes with all of the adapters you may need to power it if you have a power supply without an 8 pin connector, which is a nice plus. Having had to make 90 minute round trips to a computer store in the past because I was missing a 2.99 adapter, this was appreciated.
As far as performance, my 6950 ran Battlefield 4 at medium settings, but couldn't do much better. Anything higher and I would get low framerates. After installing this card I decided to just turn everything up to ultra to see how it did and I was more than a little impressed. I played for about 30 minutes and I never saw a framerate drop below the high 50's. I then tested Shogun 2 and was really blown away. My old card struggled with this game even on medium settings, but the 770 had no problems at all. Smooth gameplay without a hiccup.
Another thing I really appreciate is a card that runs cool (it does) while remaining nearly silent (it does that too). I didn't notice much of a noise increase even under heavy load, and the temps remained well with comfortable limits.
One other thing that really needs to be mentioned is ShadowPlay. This feature is fantastic. Being able to record high resolution video with almost zero effect on framerates and gameplay is amazing. I have always wanted to record my gaming sessions, but apps like fraps really require a very high end rig to do it right, and I was always frustrated with the video quality. With ShadowPlay it isn't an issue. I recorded a few minutes of Battlefield 4 and was actually wondering if the recorder was working since I am so used to huge framerate drops when recording. When I looked at the video I was even more amazed at the quality.
I should also mention that "ShadowPlay can be configured to record continuously with a rolling buffer of customizable length, allowing the user to save the video retrospectively if something interesting has happened in their game, without having to remember to start recording beforehand." (Wikipedia) This is awesome. I have had a ton of moments in games that I wish I had recorded, and now you can capture them all. To be honest, this feature alone is almost worth the purchase price for me.
To sum up, this is a fantastic card. My main concern was getting another couple of years out of my cpu/ram/board and I have no doubt that this card will allow that and then some. The added features like ShadowPlay only make it more amazing.
For anyone interested in how ShadowPlay works, here is a pretty good wikipedia article about it.