Love this show and currently running for the second time. Going the way it is, I might even go for a third run if only Prime maintains it. Deeply impressed by the methodical crime solving of Watson and Holmes.
The character development is too good and the chemistry between Holmes and Watson is amazing. I was glued from the first episode and I really loved the way their characters and bonding developed. Another great character is Gregson (Aidan Quinn). His character is simply inspiring and he has played the role perfectly. So does Bell (John M Hill)
I have seen the BBC version (Cumberbatch) too, but I felt it was a total waste of time. In fact the Sherlock Holmes in the 80's (Jeremy Brett) may be better than the Cumberbatch series.
The series needs concentration and needs to watched in sequence to really understand and enjoy. However at no point it is boring or will let you wander. It makes me happy that there are close to 125 episodes as I love the series and so far haven't got tired even in the second run.