Sean over at "Pod" has written an excellent post on why The Clash are so damn good, and what is missing in some of today's music. Here is a porition of what he has to say, visit him for the rest (there are also some great videos included in his post)
Double albums are tricky as you really have to vary the pace to maintain interest throughout. No such issues arise with "London Calling". The Clash take rock, pop, punk, reggae and ska, mix it up and blast it back with lyrics that touch on many themes. Lots of energy and real human beings playing the shit out of their instruments results in an urgency that reaches out of the speakers and demands to be heard.
Current popular music has many deficiencies. Most notably: 1) It's BORING 2) Most of it sounds fake. 3) Zero energy
This stuff is almost thirty years old and sounds as if it was released last week. The main reason? It didn't take them three years to record! In a matter of weeks, they hit these songs hard with a minimum amount of takes and retained an excitement that is sorely lacking in today's homogenized product.