Sometimes I think it's a bit cultishly overstated by fandom how much of a return to form the McCoy era actually was. It certainly wasn't a return to the Hinchcliffe era. It was an improvement on the Saward era and Season 24, but that's not exactly difficult.
I agree in principle with what Cartmel felt the show needed to do to fix the problems with Saward era (namely getting away from the nastiness, nihilism, moral murkiness, and the Doctor being ineffectual), but often the McCoy stories felt like a gross overcorrection with too much whimsy and adolescent right-on political posturing, the Doctor being too powerful and too able to intimidate officialdom to be believable.
I think overall Remembrance of the Daleks is the one that gets the balance rightest, and in that, the McCoy era does briefly become magnificent and more than the sum of its parts. and indeed makes me weep that we couldn't have gotten scripts like that far sooner.
The Happiness Patrol has some gem scenes in it worthy of a short film masterpiece, but also moments of utter cringe. The balance is a bit off, and as a result between a great beginning and ending, it's a bit forgettable and meandering. Plus the Doctor's part in killing Fifi does leave a bit of a nasty taste.
Silver Nemesis is a mess, and is as sloppy as the McCoy era ever got, but there is an infectious sense of the cast and makers having terrific fun making it all the same. which does make me a bit more inclined to pick it off the shelf for a rewatch occasionally. It's a bit of a tempting guilty pleasure for me, I think.
Greatest Show in the Galaxy is actually among my favourites of the McCoy era. I feel like it's one of those stories that shouldn't work but somehow does. It's compelling, eerie, delightful, and completely off the wall. It's lightning in a bottle, I think.
Overall I think that's a good average.