Here are a couple of Nimoy's direct quotes on the matter:
"[T]he making of that first movie was very dispiriting; very depressing. We had a bad script. A bad script that just never worked. It was always a struggle to figure out how to bring some life to this project."
"The pendulum swung completely when that first movie came along from being an actor- and character-oriented
Star Trek to an effects-oriented
Star Trek. And the feeling was, 'well we didn't have the money before, now we've got the money we've gotta give them a big effects movie.' So it was all about the ship, the ship, the ship and this effect and that effect and we're going through this thing and now we're going through that thing. Nothing about the characters. So it was frustrating and depressing. Very painful."
Again, I just don't see it. I feel like we're looking at two different movies. Yes, of course, they spent a lot of time and money on giving good visual effects that couldn't be had in the TV series. However, I don't feel like that was to the exclusion of the characters. Quite the contrary. I thought the story served the characters, and particularly the "big three," very well. Spock in particular had tons of character development.
Also, I think it's often forgotten that some of the "starship porn" of the Enterprise, particularly the long sequence with Kirk and Scotty in the travel pod, were not just visual effects feasts but were actually about the character of Kirk. We're seeing the Enterprise as Kirk is seeing her. And we realize that this is his one true love affair and what has been missing from his life.