For web browsing and gaming, but no competitive FPS. Mainly MOBA/Guild Wars 2 so ms isn't that important.
I really loved the G400, the weight, shape, the clickity action of the scrollwheel (don't like the friction-less ones), the position of the "back/forward" buttons on the side. I really wish there were a wireless version of it. Price is an issue though and the G700 also has too many buttons for me.
P.S. In case anyone's run into this before, My G400 is malfunctioning. Random disconnect/reconnects, sometimes stop being responsive while not disconnected, tried plugging in another mouse at the same time and that one was working when the g400 wasn't so i'm guessing it's not my computer. Have disabled computer turning off power to USB hubs to save power to no avail.