There are certainly areas where C-More just isn't going to cut it, like if you want to gather data or are doing something pretty complex. That said, if you are just wanting to have indicators or push buttons and don't really care about scripting or recipes, then I have found it hard to beat the C-More. I think the software costs about $150 and has free upgrades for life. The panels seem to hold up at least as good as PVP 600's in our plant and are a fraction of the cost. I am currently using C-More panels for any new project and have even went back and replaced a few PVP 600's with a C-More. The currenty project I am working on is replacing a Panelview 1200 with a 15" C-More.
The vast majority of instances where I have a panel mounted I am not using even a minuscule amount of what an AB panel can do. I simply do not need that. So for the price, it is hard for me to justify spending the extra $ for AB vs AD.
Another interesting tidbit, I once had to call their tech support and both the receptionist and the tech support guy had very distinct Southern US accents. As it turned out, I was having a "not really here" day and had my subnet entered incorrectly so the error was squarely my fault, both in entering it and not catching it.
The pros: Price!, intuitive software, does the majority (if not everything) I need in an HMI.
Cons: Not as capable as an AB panel, AD has no local rep/support if you needed it though there phone support is good.