Saw this this weekend. Not horrible. Actually pretty funny at times. Biggest problem is there were just too many misses. Like nothing with Helms and the rest of the family lined up. It's like he and they were in two different movies. Don't really think it's a casting problem as much as the writers really had no idea how to handle his character.
I would actually even be interested in a sequel if they can write Rusty better. Applegate, Mann, Hemsworth, and even the kids were all fine and not even written that bad. They just need to tone down Rusty. Clark at his best was never a moron, just unfortunate. Often. They made Rusty too much of a moron at times, but then other times he was actually ok. Very uneven.