Numbthreers: Dumb title, decent show I've liked the show so far, though I can see the Mathematics as a Crime-Solving Tool angle will get old pretty quick. I don't necessarily think that will be a crippling problem for this show, however, because it isn't a flat-out procedural like the CSIs are. It's really a more old-fashioned show than that, more like some of the dramas from the 70s and 80s. If Numbthreers were really another CSI clone, we wouldn't have all the back story about Charley and Don's mother's death, nor would their father be a regular character.
I'm particularly liking Krumholtz, who has turned out to be very different from what I would have expected. Most surprisingly of all, he turned out to be CUTE. He was a fairly stereotypically nerdy Jewish boy as a teenager, but the big-eyed, shaggy-haired socially awkward angelic genius role fits him like a glove. In another actor's hands, it would likely be pretty cloying, but Krumholtz underplays it nicely.
Rob Morrow and Judd Hirsch are more typical characters, with more workmanlike performances so far, but the chemistry between the three Eppeses is fine. The other characters will be developing as the show ages, so we'll see how they turn out.
As I said, I suspect they will have to leave aside the specific formula they've laid out for the show so far, because even if they manage to come up with dozens of plots which hinge on some permutation of mathematics, the theme is certain to quickly grow repetitive and even self-parodying before too long. Since they have supplied interesting characters, though, change-of-pace plots should be just as watchable as the ones done up to now.