Okay, so i've played through this remaster all the way to the good ending, and here are my thoughts, both good and bad:
I like the addition of updated sprites for both Sonic and Tails. Especially Tails, since in OG and '12 he only had his Sonic 2 sprites, which made him look a bit off compared to Sonic. I also noticed an upgrade on Sonic's sprites as well, to match his ATS look.
Widescreen is nice, though it does have its little issues such as the "Act Clear" screens being positioned to the right instead of on the center of the screen.
Some visual effects also seem to not function properly, for example, defeating the Lost Levels boss would have the screen slowly fade into white as the sprites become black silhouettes in the original and '12. Here, the background immediately cuts to white, and so does everything else into silhouettes. Though, i wonder if it's just my PC doing that. Update: So i tested the '12 version of Before the Sequel, and these issues don't seem to happen there. Apparently it's only this version of the game, so i doubt it's a pc specs-related problem.
The cutscenes definitely need some more work. It's understandable that you had to settle for recreations now that Flash (which the original cutscenes depended on) has pretty much died last year. Even then, they look rather lacking and unfinished compared to the OG cutscenes. The movements look very off, many effects are missing... And these text boxes during the last few cutscenes are... a pretty weird choice. I feel it would've just been better to keep in these little bubbles the original went for. And it probably wouldn't have been too hard to keep in the little "Tails!" voice line from the OVA, right?
Speaking of cutscenes, i like the fact you re-implemented the unused pre-Hilltop Heights cutscene, i'll give you that.
Drop Dash is a pretty welcome addition, i like it, yeah? Problem is, though, it repeats the same mistake After The Sequel DX did-- Having the Drop Dash function by jumping and not letting go of the button, instead of jumping, pressing the jump button again midair and holding it down as it officially worked in Mania.
By the way, what happened to the laser puzzle gimmicks in Metro Madness? In previous versions of the game you had to jump on a switch to make a cannon shoot a laser into one or two targets to open a door and progress along the stage. There were plenty of these. But here, the doors are already open and the laser cannon isn't functional. I'll admit it had me pretty confused.
I loved the detail of Tails flying up and waiting for you at the goalpost during Titanic Tower 1. What i didn't expect though, was that Tails actually followed you around throughout Acts 2 and 3 like an AI-controlled character! I was pretty impressed, since i don't remember seeing the Sonic Worlds framework do this before. Though i will admit, its... rather loose movement was pretty janky, seeing how it had trouble trying to follow Sonic around.
By the way, a small bug i'd like to point out, but for some reason the Act Clear screen in Arcane Altitude 1 is a bit glitched.
Overall, while i do think it needs improvement in some areas, i actually thought this was a pretty okay experience for a Before The Sequel remaster. Had fun, but some tweaks and stuff here and there would do wonders.