I assume you mean x264s? Think of them like DivX - you'd be pretty happy with a 700MB DivX of a DVD most of the time if you just wanted a quick download; these are basically the same thing for HD.
The resolution is still there, just the bitrate's a bit lower, the same as a DivX dvdrip. Perfectly watchable unless you're 2" from the screen and looking for the blockiness.