I bought my husband a G3 a year ago last March for his mbuna tank. He loves it, but he loves all things with gadgets, gimmicks, bells and whistles.
It filters beautifully.
I dislike it because of the all the alert lights are distracting and seem to go off at the slightest change, no matter how minute. Also, the internal fine micron filter fills up with gunk very quickly and slows down the flow.
With that said, it is also the easiest canister filter for cleaning, and we have a large variety of them, including the FX5, smaller fluval connisters, several different sizes of Ehiem, classics and echos, some of those knockoff aquatops, a rena, and 2 hot magnums.