I really enjoyed it. It was a little on the long side - a film of that length really neeRAB plot and pace to sustain it, and this doesn't really have that.
But, yes, it is remarkable for Adam Sandler's excellent performance - and Seth Rogan is pretty good, too.
I don't agree that it is unfunny, though. Many of the quips and potential jokes between the various comedians are very funny indeed, but sometimes got lost in the script, and if no one in the cinema laughs, very easy to miss.