As always, people getting outraged at EDGE review scores without reading the reviews. As mentioned, they use the whole scale, and usually reserve 8s or 9s to the best games of the year.
Here were their criticisms for Ratchet & Clank that justify it being just solid (a 6 doesn't mean they tear it apart like that number means for other outlets):
"Disregarding spinoffs, this is the tenth Ratchet & Clank game, and anyone possessing even a passing familiarity with the series will have a good idea of what to expect. For its part, Insomniac has no intention of failing to meet those expectations - and seemingly, little desire to surpass or subvert them."
"Occasionally, you'll play as Clank, solving marginally more complex conundrums that tend to involve more busywork than mental exertion."
"It may never quite set your pulse spiking, but rarely will you find yourself letting out an irritated huff."
"And though the script is full of characters you occasionally wish would stop talking, there's something endearing about its ceaseless attempts to make you smile. Once or twice, it might even succeed. Hardly an enviable hit rate, but it's more than many games manage."
"If technology's inexorable march suggests Ratchet & Clank may be among the last of its kind, there are plenty who would respond with a disinterested shrug. This, in truth, will do little to sway that opinion. Nonetheless, it's solid, three-star entertainment: as pretty as it is inconsequential, as likely to be thoroughly enjoyed for the dozen hours it lasts as it is to be forgotten within weeks. It's not taxing or provocative, it will leave you neither upset nor elated; it simply wants to give you a good time. Sometimes that's enough."
On the new weapons:
"There are fresh additions, too. The Proton Drum fires out throbbing pink shockwaves that zap anything caught within their radius, while the Pixeliser is an instant classic: a shotgun that turns enemies into blocky sprites, eventually causing them to fragment into voxels."