I started watching it, and Heather and I finished the first season. It was pretty good. I don't know that I think it's nearly as good as I'd been led to believe, and a quick preview of season 2 had me groaning (oh of course we need to make Irene Adler a dominatrix ... that makes total sense. Christ. When is the public fascination with BDSM going to fucking die off already? It's so overused and cliched and boring), but it's a pretty good show, and kind of a fun romp through assorted Sherlockian nonsense. I enjoy the little references to the original material, though they're generally quite small. I wasn't quite sure what to expect, so on some levels I've been fairly impressed, on others somewhat disappointed.
Bear in mind I'm a big fan of all things Sherlock and have been for years. I've read all the original stories two or three times over, and own some other spin-off material using the characters and style. I actually really enjoyed the Guy Ritchie movies for being as different and fun as they were. Robert Downey Jr. was just perfect. So I do like this show, but not as much as I was hoping to.