>>>All in all I'd say he stayed at the party two years too long.
My feeling at the time was that he was "hogging" Cap to himself unjustifiably, i.e., that his work on Cap wasn't that good to really deserve being on the title so long. I enjoyed his initial work, introducing characters like Flag-Smasher and that "Justice is Served!" villain. Then he introduced D-Man, who I didn't like. Then he took away Cap's costume and Cap had to become The Captain. At the time, this looked to me like an attempt at doing his own "Nomad" storyline (Englehart era) but not as well. I didn't like it, and stopped buying it around that period. The last Gru issue I bought new was #356, and I didn't buy another Cap comic till Waid's first 2 issues. It was almost like I'd been waiting for Gru to leave before I was willing to buy Cap again. (To be fair, I had stopped buying most new comics during that time.)
Later, in the mid-to-late 1990s, I started picking up much of Gru's Cap run in the cheap boxes at comics conventions and found that I enjoyed some of the ones I'd missed. Cap #401 was a stand-out issue, as was "The Bloodstone Saga" arc. There was some good stuff here & there, but also some stuff that seemed gimmicky -- done for commercial and not creative reasons. Also, the comic didn't seem to have as much of an intelligent and credible manner (real life and politics, etc.) as it had in its best runs (Englehart, Stern and DeMatteis).
Even though I like some of Gru's issues, I do think that you could have put almost anyone on those issues from 1985 to 1994 and still probably would have had as enjoyable (or perhaps more enjoyable) comics as were done by Gru. But we'll never know for sure, because he stayed on the title so long.
I loved the Captain and his hand-picked commandoes. That was the only reason I started buying Cap. I would have been happy if that plot arc had been dragged out for another one or two years, particularly after Diamondback breezed in.
The latter stories were a bit meh, although I have a soft spot for Free Spirit. She needed a decent name, some decent powers or a gimmick (if you've gotta pump it, pump it with a turmpet) but generally I like the look and her personality. If anything, she was squandered by the decision to bring in Jack Flag.