You either like this sort of humor or you don't. It's not exactly my favorite flavor of comedy, but I know what it looks like when it's working versus when it's not. The jokes are easy and the targets are broad and cheap, but there are more hits than misses, though the misses tend to be the longer, drawn-out bits and there are a few too many. Sandler's sensibilities generally aren't my cup of tea (there are only so many times "Oh, god, did he really just do/say that?" can work as a punchline in one movie) but this is easily the best his signature style has worked in a long time and the basic formula of "Donny does something horrific, Han/Todd looks frantic and uneasy" works comedically and will probably hit home for audience members with less than perfect parents of their own.
What actually seems to be the biggest help of all is that, while the majority of Sandler's films have been PG-13 versions of his very R-rated live/album persona, That's My Boy actually goes for the R. It almost sounds like a betrayal of taste to suggest that allowing grosser visuals and raunchier jokes is a huge improvement, but it does help things feel more naturalistic. Operating on a scatological plane only slightly stickier than Beavis & Butthead or Ren & Stimpy worked for Sandler back when he was a younger comic making movies aimed at younger teenagers, but as his fanbase and comic perspective grew up (or at least grew older) the Junior High puerility felt more and more out of place - see: Jack & Jill.
If nothing else, freedom from the PG-13 constraints allows the film to follow Sandler and company's standard bad-taste gags to their darkest logical extremes. The opening scenes involving young Donny and his teacher are profoundly uncomfortable, which helps the expectedly obvious gags ("Ha! She wrote a dirty message on his pop quiz!") work - in a relative sense - as cathartic release. A running subplot involving Meester and her psychotically overprotective Marine brother (Milo Ventimiglia) works over a familiar gag from other "meeting wacky soon-to-be in-laws" movies, but takes it right up to the edge, and then jumps over it with sicko/show-off glee in an extended scene that had my shocked preview screening audience gasping/guffawing so loudly I missed a good bit of the dialogue (though it mostly seemed to consist of Donny gagging and looking bewildered). It's kind of incredible that Meester and Ventimiglia - both considered to be rising stars with reputations to consider - agreed to participate in what's probably going to wind up being a notorious "I can't look at that dude/chick the same now" moment.
In fact, the main thing that seems to keep the film stranded in "pretty good for what it is" territory instead of just simply "pretty good" (apart from the not funny parts being really not funny) is the presence of Sandler himself - he's miscast in his own movie.
I won't deny that Sandler is a tremendous comic talent - anyone who's seen his SNL work or especially his live shows can attest to that - but his best work acting-wise has always been as the straight man to wackier characters around him. The better Sandler movies have consistently been the ones where he was the normal guy (think Billy Madison, Wedding Singer, Click) while his funny-voice/mannerism bits in Little Nicky or The Waterboy grated.
Donny Berger: The Dad From Hell should be a much darker, meaner, more dangerous character (think Gary Cole as Reese Bobby in Talladega Nights) to keep the tension of the situation high, but he isn't - even though he's been written that way - because it's so clearly just Adam Sandler in cartoonishly-disheveled clothes and a bad wig doing a funny "Drunk Boston Guy" voice. A nearly homeless-looking vagrant stumbling around an upscale cocktail party, Budweiser in hand, looking ready to start punching/groping/defiling anything that moves should be alternately threatening or pathetic, but here it's just "Aw, it's okay - it's just Adam Sandler doing 'Drunk Boston Guy.'") Midway through the screening, it occurred to me that any number of Sandler's perennial sidekicks (particularly David Spade or Rob Schneider, who're both better at character work than he is) might've been better in the role.
I can't in good conscience recommend that anyone see That's My Boy, but I was surprised to find myself not actively despising it - if nothing else, it's not nearly the complete conceptual/execution failure that Rock of Ages is. Most things have an audience, that audience isn't always me, but people who feel like they might like That's My Boy probably will.
Bob Chipman is a film critic and independent filmmaker. If you've heard of him before, you have officially been spending way too much time on the internet.