I can't understand other IMDB members' criticism of this very funny show. If you like Steven Moffat's other shows, how can you fail to be amused by this? Very much in the same vein as the previous "Joking Apart" and the latter "Coupling," "Chalk" puts its characters into farcical situations from which they have to find their way out of -- and suffer a world of embarrassment while doing so.
The writing sparkles, and the acting is superb. The cast understand the meaning of the words "comic timing." And no, I did not find the performance of David Bamber, as Mr. Slatt, "over the top."
Speaking of Mr. Slatt, you've got to love that the character starts out -- to use the British vernacular -- a total w****r. But then, in the episode where Mrs. Trippley meets her online sex partner (who goes by the screen name "Meat Helmet," while the dowdy, middle-aged teacher is "Hot Bitch" C'mon, tell me that that alone isn't already making you chuckle), Slatt is actually allowed to be heroic! This is akin to having M*A*S*H*'s Frank Burns turn around and do something noble at the end of an episode. Slatt's honorable action is totally unexpected, but a nice bit of character development nonetheless.
All-in-all I'd say don't be put off by a couple of negative reviews. If you like Steven Moffat, or you like farce, watch this show! Meanwhile, I wish someone would put out a Region 1 DVD of "Chalk" so that I can see the episodes that I missed when it ran on our local PBS station, and re-watch some of my favorite episode, such as the one mentioned above.