Better than Flows in many ways, but not in build quality
I have the 2012 GNU Choice. If you do your research online, you will find some people who hate these and some that swear by them. I'm in the middle. The rear entry system is just the best there is. It's so good that even Flow changed their designs for 2013 to adapt the features that these bindings offer. The two-point rear entry is just awesome because it's fast and feels almost exactly like a traditional 2-strap binding when you're bombing the run. Control is great with these bindings but the highback does feel somewhat flexy. You can never really make these bindings "stiff" but for most people they will probably be using these more for park boards anyway.
The biggest problem with these bindings are the build quality and choice of materials. For one, they cheaped out on the strap fasteners. Instead of traditional ratchets, they're using cheap plastic ratchet-substitute things that aren't long enough on the toe cap and don't hold particularly well on the rear. The idea is you "set and forget" your strap tightness, but in execution I find that the toe cap comes loose fairly easily. Even when the toe cap isn't loose it doesn't feel like it's actually providing any support or pressure on my boot, which makes it worthless. I've heard of some guys using zip ties on the fasteners because the factory fasteners just suck. Usually it's not a big deal but ultimately I feel like the toe cap doesn't do anything.
The spring-loaded latches on the rear straps that allow for the unique entry are really great, when they work. Both of mine got very gunked up on the runs just after a few days and sometimes they failed to pop up when I was exiting the binding. I contacted GNU and they sent me solid-metal replacements that do the job nicely. A+ for GNU customer service. Since then they work much better, but they should have been better build quality from the get go. I love the lift hill release feature of the bindings, but ultimately all it does is change the pressure point on your foot, since you're still ultimately carrying the board either way. Still, it's a welcome feature and works well when I want it.
Ultimately if Gnu would just use better materials and rethink the fastening mechanisms for the straps, this could beat everything Flow offers. Right now I would say I probably wouldn't buy them again until they fix most of the issues I mentioned.