The i7 is faster than anything from AMD in many benchmarks. If you're looking at AMD I would consider the newer 8350 over the 8150, it's a better chip. In some cases the 8 core AMD is faster than the 3770, usually in certain heavily threaded applications like rendering or video encoding, but it's usually just barely faster. Even in multi-threaded applications the i7 is often faster, depends on the program. Single threaded tasks the i7 is universally quicker, sometimes by a large margin.
In short, the i7 is faster at almost everything, sometimes by large margins. When the AMD 8350 occassionally wins a benchmark, it's not by much.
Is the i7 worth the price premium? You certainly don't get a 50% performance increase for for a 50% price increase. Either one will perform admirably.
Here's a photoshop bench from a well respected tech site. The whole review is worth a read.http://www.anandtech.com/show/6396/the-vishera-review-amd-fx8350-fx8320-fx6300-and-fx4300-tested/4