Thanks for all the responses everyone, wasn't expecting to open quite such a can of worms on this one...! Think based on everyone's feedback I'll likely give it a miss - I don't have loads of time for gaming nowadays anyway since having kids, so if the best most people can say is that it's "okay", "aggressively mediocre" or "not offensively bad" then I'm probably better off saving that money to eventually put towards something else better. To be honest, I didn't feel the need to pick it up in 2017 when I had way more time and budget - and it's not like I'd completely fallen out of the Sonic series back then or anything, I did pick up and play the hell out of Sonic Mania - so what I've heard from folks here just seems to reinforce that my original decision was probably the right one for me. Revisiting Sonic Generations is scratching that itch for boost-style gameplay at present anyway, and after that I still have Shadow Generations to look forward to which seems to be very well-received. So I'll just content myself with those for the time being, and then look forward to seeing what the next instalment of the series will bring.
McAleeCh got their answer. Can we now flush this whole thread? Please? EDIT: Or just the toilet posts. That's fine too.
For whatever reason Forces completely passed my radar at that time. I was aware of Lost World and its many ancillary materials and Boom being a thing, but Forces kind of slipped through. It's the one Sonic game that I'm not entirely familiar with whereas everything else I've seen videos of. It's the Ninja Turtles The Next Mutation of the series.