Big Daddy is the cinematic equivalent of your uncle who thinks he's hilarious at Thanksgiving—there's genuine heart buried in there, but you have to wade through a lot of questionable jokes to find it.
The core story about an immature guy learning actual responsibility and forming a real bond with a kid is legitimately touching. The problem is that the journey there involves teaching a five-year-old to trip rollerbladers, pee on buildings, and generally behave like chaos incarnate—all played for laughs. For parents trying to model good behavior, this is... not it.
The humor is peak late-90s Sandler: crude, juvenile, and hasn't aged particularly gracefully. Modern kids might find it more confusing than funny, and the cultural references are prehistoric by their standards. The TMDB rating of 6.5/10 suggests audiences found it 'fine'—which is about right.
If you're looking for a family movie that teaches responsibility, there are better options. If you're feeling nostalgic for the Billy Madison era and want to explain to your tween why people thought this stuff was hilarious in 1999, go for it—but watch it with them so you can provide real-time commentary on why we don't actually parent this way.
