You will definitely notice in a certain minute-long part of a season 5 episode ("Power Play"), but fate is fortuitous since most of the footage involved in that episode were wide shots or with softer backgrounds. It'll be noticed but nowhere near as jarring as it otherwise could have been.
You'll only see sharpness loss. The grading process used to match the NTSC videotape (VT) to the original 35mm is quite a phenomenal match given the limitations of VT, especially if you understand how technicians back in the day changed "National Television System Committee" to "Never The Same Color" as a form of a joke... can't blame them TBH...
Most of the issues, which ALF pointed out, are very brief indeed. Seeing whole episodes as a blurry jagged upscale might not be as fun, however.
Indeed, given the scope of the project, the fact so little was not recoverable is pretty awesome in of itself.