I think Sonic Forces is actually a pretty decent game. Was it a disappointment considering it was supposed to be an anniversary title? Well yes, but that's why we have Mania, right?
On its own though, its actually not so bad. I was afraid I was going to get bored of it, but the more I play it, the better it seems to get. My only real complaint about the game is it was too short for what it's worth. There was so much potential wasted, along with the story needing to be rewritten. The gameplay itself is pretty fine though. It plays well, the controls are simple. The Switch version could honestly be inspiration for a Generations port using the same controls.
Basically, it's not the best Sonic game, but I like it for what it ended up being. I think people need to try giving it a second chance. This is just my opinion though, so don't quote me on that.
Hell yeah, the plot was a little more serious, you know ? the only thing that is not "so cool" is the fect the stages are very short in my opinion