I love TOSR. The new planets and angle shots alone are worth it. But we got so much more. New ships (and the TAS Antares class making some great cameos), real battles, different versions of matte paintings (and some great new ones as well)
what's most important for me is that most of the "important" episodes got very good treatment. Journey to Babel, The Menagerie for example. Amazing work.
In The ultimate computer we got the new space station with a docked connie, some ship-on-ship battle scenes, great angle shots of the fleet and a nice farewell shot. Why complain? It might have been done better, but we did get some good stuff.
The only real TOSR disappointments for me were Balance of Terror and of course Errand of Mercy.
In Ultimate I can see why they didn't use another ship.
There was really only the constitution before Khan, and they didn't really need a new ship for such a small fleet, especially considering those were supposed to be the cream of the crop. I certainly wouldn't have liked some non-canon vessel. MAYBE a TOS-ified Miranda. But using connies only was okay in my book.
In Errand, this approach did not work. What angers me most is that we DID see the scout in TOS. They should have used that design, even if it looks odd
And a huge cloud of D-7s could have worked for the Kling fleet as well, but it was done badly.