For me, the art in shadowrun has gone downhill since SR2, when there was some REALLY great images. The latest SR4A stuff is not too bad. Augmentation, Arsenal, etc - I bought those books DESPITE the art. I like the new Arsenal better. I confess I do like some SR4 covers, eg Runners Companion. But not many.
There's some fantastic SR art coming out of the Cliffhanger Shadowrun online game website, and the shadowrun returns game site too, if you havent seen those already...