I tend to be a little wary of SPs done after successful dramas, as in the past I've noticed many of those being way below their respective main series' level (and more generally, way below par!)...and this "Tokyo Tarareba Musume 2020" was no exception, unfortunately.
Whereas with the original series I had liked more or less everything but the last episode(s), here I kinda like the last 50' or so, but on the other hand I couldn't help but finding the first 45' terribly boring (the definition "yawnfest" comes to mind) and borderline annoying.
The cast did well though, all things considered, particularly Yoshitaka Yuriko and Oshima Yuko (who's been nothing short of brilliant in everything I've seen her in so far!).
If you asked me about the music - despite the fact that I've watched this, like, less than 24 hours ago! - I'd have to reply that I don't even remember the music in it (which means it wasn't terrible, but also not very good).
All in all, once again a SP episode ends up being...nothing special! :/