Coventry isn't that bad on the whole. Sure, Wood End is an absolute dump, and Hillfields can be scary, but there are nice parts like Earlsdon. The city centre is slowly being done up, as they remove the drab modernist lumps.  
However, I know that Aston is a craphole from seeing Rovers play Villa a couple of times, and going through it to the Thinktank place as part of my post grad course.