Here's a description that can be found on Wikipedia:
Filming took place at various locations, including London and Cardiff. The three-part series was transmitted on BBC One and BBC HD, in July and August 2010. The critical reception was mostly very positive. These episodes, along with the unaired pilot, will be released on DVD and Blu-ray in the UK on 30 August 2010.The series, though I just watched one, the third, is really enigmatic and keeps you locked to the screen - 'specially if you really like Sir Arthur Conan Doyle's work and the previous TV/movies ... for a want of a better word, editions.
You can watch the first three parts, it's available online, just ... surf t h e web and its channels, if you catch my drift.
Oh, and you may want to check out that blog/site Holmes is using in the show: just google it.