Alright, I'll make this simple. Brevity is the soul of wit, as some say.
As it stands, I have 2 (two) gripes with how the spindash is currently implemented.
1. It's too slow, as stupid as this sounds. Don't get me wrong, max rev is definitely worth it, but when I see a 1-rev spindash giving me a light tap on the back all "haha kid here's your speeps" I feel like permanently unbinding the spin button on my config file.
2, and the main problem I have with this ability, it feels like a gimmick instead of a tool. (No, Tails, you're not allowed a say in this.)
A bit of a plea as this somewhat dives into Sonic ability territory so please focus on how it affects the spindash and don't derail this, aight?
I hear time and time again about how SRB2 should feel faithful to the classic games. And I gotta say, the spindash here definitely isn't faithful at all. Manual vs auto charging aside, I'd like to ask how much you should actually use the spindash in SRB2, with Sonic specifically. I'll answer for you: if you want to go fast, you wish you wouldn't need to spindash at all. Sonic is just thok after thok after thok after thok, with frame 1 jumping as the inbetweens to preserve those chrunchy 60 fracunits per tic. But Sonic does have to spindash sometimes. Not for speed, obviously, but for entering spin-only segments in path splits. You know that DSZ2 spinning wheel? You'd spindash there, and that's it. Bye-bye, spin button, I certainly won't miss you.
In other news, Tails spams the spindash on every single level. Spindashing with Knuckles is encouraged, especially after landing from a glide. The easiest way for Metal to enter Boost Mode fast is by charging a spindash about halfway through. And over there in the left corner, Sonic spindashes for a split second to get into a dedicated spin character section. Gameplay.
And to make things worse this behavior is exclusive to SRB2! No other Sonic game that has ever had the spindash is actively deincentivizing you to use it. In Sonic 2, it's a tool for speed. In 3&K, it's a tool for speed. In Adventure 1, it's his entire gameplay, although you can certainly see why this missed the mark. I tend to mock Sonic Labyrinth for how amusingly stupid it is but it still has a spindash that serves its purpose.
I bothered to check our current Sonic world record, and found out that, excluding the half-second spindashes in GFZ2 and the Fang boss fight, the spindash is used around 10 times. Ten. In a campaign with over 20 levels? Need I say more to prove my point?