Sonic Advance is the game that originally got me into the Sonic series when I was a kid. Way back when I actually played games that required, you know, passable reflex skills. Nowadays I stick to turn-based RPGs and cozy games.

That being said, I have fond memories of the Sonic Advance series. The pixel art is fantastic, enough of its levels were playable at my skill level for me to coast off of my siblings unlocking the stuff I couldn't beat, and it kickstarted a long-running franchise obsession that I am forever grateful for.

I love all the Sonic Advance games, and occasionally I still replay Advance 1.

I agree with most of what you said... Advance 1 is closer to the classic formula, so it can appeal to a wider range of Sonic fans compared to the sequels which are usually love or hate depending on your tastes.

The level design is solid, though there are a few places where it gets a bit unfair with hazard that you can't anticipate (like when you have to fall blind upside down into a maze of off-screen spikes at the end of Cosmic Angel) or places where you have to rely on janky collisions in order to progress (mostly in Egg Rocket). The classics have their unfair/janky/bad designed places too, this is not much different in that regard, still nothing that ruins the experience too much.

Regarding the bosses, they are nice, the only one that I don't like is the final one (not the extra boss, the regular final boss)... it's annoying, has weird collisions, and doesn't look like a final boss at all... visually it's just the usual gimmick attached to the Egg Mobile, looks like a regular zone boss.

The special stages are great, probably my favorites in all the franchise (I also like the Advance 2 ones, but Advance 1's are better designed despite being simpler in concept - a twist on Sonic 2's half pipe). They are very fair, can be completed on the first try without memorization; the only issue is, as you said, the perception of depth and the collisions, which are kinda solid but hard to read.

Regarding Amy, her gameplay is very fun actually, though it's not very intuitive. There are ways to hit enemise while staying safe, build up speed and abuse of the acrobatic tricks to reach higher platforms that normally you wouldn't reach unless you fly or glide. Actually, Amy is my favorite part of the game, except for when you have to fight that final boss offcourse.

The acrobatic flip can be activated while you run, just tap down for a frame, you don't have to slow down or crouch at all (if you do it precise enough, you can keep all or most of your momentum, and you can do it while running vertically on walls too); it's possible to chain the flip with the bunny hop to increase its horizontal range when there's not enough room to run. You can stay invincible if you bunny hop and attack in the middle of the jump arc... the downside is that when you hit the ground you have to watch an animation until the character is ready to move again; do it at the edge of a platform to fall down and cover more space, or land on a gimmick/bumper to cancel the end animation. If the enemy is directly below you, you can attack+down and bounce on it with the rotating hammer... works well on some bosses too. The bunny hop is also useful to skip some small gaps, but it's very situational (there are some skippable gaps at the beginning of Angel Island act 1 2, that place with chameleon badniks and those tiny spiked platform moving up and down).