When it comes to traditional Flows there is one huge "problem". They don't work unless your boots fit correctly. If your boots fit correctly then they will hold your foot as well as two strap bindings with less pressure, more comfort, and faster entry. There is also the fact that some people simply can't get used to not having the feeling of their foot being clamped in.
They do not do good if your stuck in powder.
The NASTY Flows solve these issues mostly. You can get out of powder easily, and you can make them clamp your foot to hell and back. Though the first year NASTY's had problems with their ratchets.
2011 Smokin Buck Ferton 155
2013 Flow NX2-SE
2013 Flow Hylite boa
Burton Stagger pants/jacket