I looked up reviews on them when I was looking into swapping my 5.7 back to injection from the initial carb install and pretty much heard nothing but good responses. I've got a friend at my work that put one on a pickup he has when the factory computer crapped out and he's pretty happy with it. Said it dialed in nice after driving it around enough. The only potential downside is that you still need ignition control, which may not be an issue depending on what engine you want to put it on.
One thing I'm not sure a lot of people know about is that they make a multi port kit as well that's designed to replace a stock system instead of going with their throttle body setup. It's more or less just the computer and a harness set up for multiple injectors, so it's a pretty nice price ($800-900 I think), though that may be without their fuel pump. Not sure what all applications they offer it for though (I think they had a Chrysler kit). I was looking into that when I got the 5.7, but ran across a used Megasquirt kit and went that route.