How is "overall better transfer" different from "added visual quality"?
What I mean is, if you went and bought, say...The Dark Knight Rises
on both DVD and Blu-ray and played them on your old TV, they'd look about the same. With TNG
though, the old masters that were used for TV, VHS, and DVD are quite crummy. They were produced on videotape and it shows. The TNG
Blu-rays have been rebuilt from the ground up and show considerable improvement in all areas that would be apparent even on an analog TV. There's simply no contest. I have checked this myself on the old TV I have in the spare room.
Whether or not that improvement is worth a purchase is up to the individual though, of course.