Amazing Spider-Man #151-180 is a significant Spider-Man run that isn't discussed a whole lot, so I'm curious as to what the opinions are. Len Wein was the third major writer on Spider-Man, and he had a distinctive run that built to a five-issue final arc.
To explain the potential scores, as it's possible for one man's B to be another man's C...
An A+ is the highest score. It's meant to be pretty rare, an indication that this run is up there with the best of the medium (Frank Miller's Daredevil, Byrne/ Claremont X-Men, Neil Gaiman's Sandman, etc.)
An A is impressive, but not quite on that level. It would be among the best for the character.
A B indicates that the run is good but not great. The majority of the material is still worth rereading. In terms of quality, it's largely a success.
A C is pedestrian. It's neither good nor bad, and most of the material is probably not worth rereading.
A D is poor. It's a flat out failure. Most of the material isn't worth reading in the first place.
An F is worse.
Sal Buscuma illustrated Amazing Spider-Man #154-155. Wein didn't write the Spider-Man annuals at the time, so I'm not counting those as part of the run. Wein had an earlier run of Marvel Team-Up although that had been over for an year by the time he came to Amazing Spider-Man.