I've got a G810 and like it. For reference, I also have a Ducky Shine 6, WASD Code and an old buckling spring Model M, as well as a couple old random Cherry branded keyboards.
Things I like about this keyboard: It is quieter than its Cherry switch stable-mates, despite having added O-rings to one of them. I like the layout. The lighting is truly worth of awe - especially after seeing the competition. It doesn't look like a gaming keyboard for the other 90% of the time.
Things I don't like: (Big One!)The lighting returns to default color wave as soon as you lock your PC, etc. Unless the logitech software is running and has access to the board, the keyboard lights up in crazy mode. You can turn the lights off all together, but that kind of defeats the purpose. Also, the key travel is not as smooth as name brand switches if you hit a key off center - I hope this improves with time. This ended up in my office since it is quieter than my other boards, having to turn off the lights so the color wave isn't running when I'm away from my desk is silly. I wish I could make it default to any solid color, or off.
Other thoughts: The keycaps could be shaped a little better, and be less prone to shine. Overall, this is a decent keyboard, at its current sell price, it may be preferable to the more expensive boards.