The cover is an easy swap out if that is all you want to to do...but like others have said, there are different hinge types so take a picture of the hinge before you go to pick up the new one. I found my whole bathroom vent screen etc pretty much looked crappy about the time that the lid was cracking, so I replaced with a fantastic fan. If you decide to do that, it too is an easy swap out. Assuming that your roof is rubber and not tpo vinyl, the fan comes with putty tape to seal it to the roof. If your roof is tpo vinyl, don't use the grey putty tape as it is not compatible...there is a white putty tape for use with that. I would seal seams and screws with dicor and then cover with eternabond tape.
FWIW, there is no comparison between fans...I am going to replace the stock bathroom fan in mine as soon as I pick it up.
Celt