The script is a little weak at times, some of the setups are a bit awkward, and the math, well, it's a TV show. Ignore the almost-always incorrect references to quantum mechanics and other math and physics mis-uses.
I like Judd Hirsch (Alex from Taxi) and Rob Morrow makes a good cop. The casting for little brother was a bit off, since the two actors have very different visages. If you ignore that, they work well together.
The main character (Charlie) consults for his brother at the FBI. The show is more of a cop show than an FBI show, but somehow the FBI is always involved, seemingly to direct the local cops. The script writers don't seem to have a clue about what the FBI does, or how municipal police work. But, again, ignore that and it is a good enough show.
Lastly, ignore the inconsistent personality traits of the characters. It would be nice if they had more consistent behavior, but maybe the budget doesn't allow for better writers. Still, it is a good show for relaxing a little and the actors are all good.