"Altered Carbon" by Robert Morgan

Robert Morgan might be an ESL teacher, but he's an amazing cyberpunk writer!  And his lack of technical background (hard science background too) make his books even more readable and romantic.  Takeshi Kovacs must be one of the best ambivalent heroes created in the last half century. He's not a bad guy, it's the circumstances.  He has a good heart, and it is obvious in the end, when he could have made much more damage and not repair anything.

The universe of Altered Carbon is fascinating.  No faster than light travel.  Colony ships that take centuries to reach their destination.  But there's 'needlecasting' - similar to the 'ansible' device in other universes, notably Hyperion.  However needlecasting apparently can transfer enormous amounts of data, unlike the ansibles that are limited to typed text.  Humans get 'downloaded' from their brains and 'needlecast' to anywhere in the Universe, where they are 'uploaded' in a 'sleeve' - a human body without a 'tenant.'  Pretty naive, but effective.  From scientific point of view there are so many problems with this kind of concept, it doesn't even start to approach reality (i.e. if humans can be downloaded on a 'spinning disk' [oh, Morgan, you should have read some basic Computer Science book, at the least] then the data is 'quantified' and as such it can be 'list'-ed and different lines of code erased or added. Where does the 'human' end then?).

Takeshi is an "Envoy" - special corps of psychologically conditioned murderers that do the dirty jobs for the UN Protectorate which rules Earth, and largely the Universe.  Envoys can enter multiple bodies ("sleeving") and still keep their sanity and adapt rapidly.  Takeshi is hired by a 'meth' (Methusalah) on Earth who has lived more than 3 centuries in various sleeves.  Then there's the sexy future-cop Ortega, with her long limbs and psychological stuck ups.  But the book is too complex to be summarized in a few paragraphs. 

Suffice to say it is one hell of a rollercoaster ride.