I've been replaying Sonic Forces lately myself and I think I was largely unfair to it. I was one of the few actually looking forward to it and I felt quite disappointed at the time, but going back and playing it now, it isn't really *that* bad.

The boost levels really do suffer from weaker level design than the previous three boost games (Luminous Forest is almost an exception, though), but the Classic and Avatar stages really aren't too bad. Classic feels a bit janky but then so did Generations' attempt.

Further to this thread, I think I figured out why so much of the game feels like "boost through hordes of robots"

Sonic Team are big on creating certain feelings or themes for each title these days - that sort of design really sells the idea that Eggman has taken over the planet

Unleashed - Traveling the world!
Colours - Wisp powers and colourful theme parks!
Generations - Happy birthday!
Lost World - Planetoids
Forces - Eggman won, post-apocalyptic, robot armies