Richard Miles' Carthage must be destroyed (2010) is a very nice read and well sourced*. It covers the entire history of Carthage from its origins in Phoenicia to its destruction by Rome.

*Edit:

as /u/Celebreth points out below, Miles' use of sources has been critisized. /u/ScipioAsina points to Serge Lancel's Carthage: A History (Oxford and Cambridge: Blackwell, 1995) and Dexter Hoyos' The Carthaginians (Oxon and New York: Routledge, 2010) as better books for an introduction to Carthage.

I really enjoyed this one here - though it's more about the Punic wars and mostly from Rome's perspective. It has some background on Carthage. My understanding is that there isn't a whole lot of information about Carthage outside of the Punic wars, though.

http://www.amazon.com/The-Fall-Carthage-265-146BC-Paperbacks/dp/0304366420

Thanks everyone must check these books out