My buddy has the PF4 in his AMC Javelin 360, and to be honest it's working really well. I will just say that it's made for guys that want to mostly set it and forget it with respect to "tuning", and programming other Engine Management type "functionality" that you would get in other systems.
For example, electric fans control is nice because it has two outputs but is limited in that it can only do relay trigger (on/off) control.
If you're an automatic trans, and you want to do some basic TCC (lockup converter) control, there isn't any of that, or any other custom I/O functionality.
You basically tell it what you want it to run as an AFR, based on a few of their canned tunes, then it will learn and closed loop self tune to that AFR. You can tweak a good amount of fuel controls, but it won't be in the form of advanced tables with a laptop and extensive control.
One of the nicest features is it's use of an android based app you can run on your phone, or a tablet to adjust, and monitor engine params live while driving. They just recently added a data logging feature which immensely improves the system imho if you're trying to resolve an issue.
All in all, I like it very much...the fact that it comes with an INTAKE, THROTTLE BODY, DISTRIBUTOR, etc, for the cost of other systems ECU only cost makes its a great choice. Especially if you want to retain the old muscle car, round air cleaner look under your hood.