Gui should have really gotten the proper Sonic CD 2011 remake, as it adds a ton of awesome new features, such as 16:9, Sonic 2 style spindash, Playable Tails, selectable Soundtracks, and a Save feature!
Sonic CD is actually a fascinating case where during it's original development, it was being developed in japan at the same time as Sonic 2, which was famously developed in the US. Both games were pretty much developed in isolation of one another. Sonic programmer Yuji Naka headed Sonic 2's production in the US, while Sonic's Character Designer, Naoto Oshima lead the Sonic CD team.
I love Sonic CD, for it's excellent (Japanese) soundtrack, the bigger emphasis on exploring the multi-tiered level design and finding ways to time travel so you could destroy all the robot generators, and just overall having a very loud and 90's atheistic to it. another thing to note is that Metallic Madness Zone 3 is the only one with a bottomless pit in it in Sonic CD, which again, feeds into the fact that the levels are built for exploring them rather than running through. as for setpieces, I would argue that Gui clearly didn't get to stages like Whacky Workbench or Stardust Speedway, which are pretty much level set piece overload to the point they turn some folks off. Workbench in particular with it being one of the most vertically inclined Sonic levels out there where the gimmick is that the lower path is the one that's impossible to stay on.
The benefit of going to the future is that good futures tend to be enemy free and really easy to rack up rings and extra lives for a special stage attempt. Bad futures tend to be the hard mode of stages, so in a way, time travel is a bit of a difficulty select and extra objective. it may not be a perfectly well implemented mechanic, but I appreciate the effort for the early 90's.
Sorry I dropped Twitter so hard. it's annoying to keep up with, and I've been embroiled in the pokemon spoilers. It sounds like you may have a ISO of the japanese or european versions, because Sonic Boom is from the US soundtrack for Sonic CD, and... is probably the one track I like from the US version over the JP/EU Sonic CD OST.
I'd argue Sonic CD is better than Sonic 2 for me. it's hard to argue it up against the behemoth that is S3+K, but like... this is a fun game that I enjoy quite a bit.
Kinda funny that the one week you call me out for getting triggered over your video game opinions I don't, and then you find something that does trigger me, huh?

I also need to stop writing these up as I listen to the show. if you need FP tips, feel free to hit me up here via PM or tweet at me so my phone actually gets a notification.