I ought to point out that this is volume three of Transmetropolitan. Read the two previous books ('Back on the Streets' & 'Lust for Life') first, as they set the scene and introduce the characters. They're also very good stories in their own right.
'Year of the Bastard' is where the main theme of Transmetropolitan takes centre stage. Spider's never been happy to simply write about the City - he wants to change it. He sees the president ("The Beast") as a symbol of everything that's wrong with the system. And it's an election year, so he finally gets his chance to shake things up...
While it still has moments of pure humour, the vicious slapstick of some earlier tales fades into the background as Spider gets entangled with spin doctors and would-be presidential candidates. This is a plot-driven tale of twists and turns, where everyone has an agenda. To reveal anything further would be to spoil it.
Just don't expect to see a resolution where the plot threads are all neatly tied - this is the first section of a longer storyline, and while there's a (very) definite ending to it, it also carries a lot of plot over into the sequel, 'The New Scum'. I think it'll carry an awful lot of readers over, too...
If you like politics, or if you loathe politics, this is well worth a look. Warren Ellis has outdone himself on this one.