Henry has two strikes against him. He has stone hands; and he couldn't abide sharing carries with McGahee, so his head may not bve screwed on tight.
But other wise he is a duplicate of Antowain Smith; Both were former first round picks of the Buffalo Bills, who had a couple of good seasons and then fell out of favor with the Bill hierarchy because they had a newer shinier toy they wanted to play with.
Like Antowain he's not a HOF back, merely good one, who will run between the tackles and get his 1000-1200 yards a year. The Patriots have won several Superbowls with a back like Henry. My concern is with what's between the ears, nothing else.
Acquiring Henry, to platoon with Cory, would allow the Patriots to finish the rebuilding of the Defense, in the draft.