How bad is it? It's an unfunny comedy.
Should you see it? Don't go out of your way, but if you like Burt Reynolds, sure.
Imagine if the Eddie Murphy character in Beverly Hills Cop were tiny and unfunny. No - you're thinking Kevin Hart.
An 8 year-old who dreams of being a cop has information the police need, but insists on being made an officer for a day. Then he's put into the hands of Burt Reynolds, who does his usual schtick. I'm not sure why this has some terrible reviews, though it has some questionable material: at one memorable point, Reynolds uses a urinal in front of the boy, who wants to swordfight and the boy ends up peeing on Reynolds' feet. There's also some mild 1980's racism. Mostly there's just jokes that don't really work.
Also inexplicable is why there are some very good reviews of this. Perhaps the child's dead-on impersonation of stereotyped cop behavior amuses some. Or the smarmy direction of Henry Winkler makes this an okay kid's film.
I say "meh."