First I want to mention that I didn't even know there was a previous "Gymnast" before reading this thread, so I cannot make any comparison.
1. The game ran perfectly, except for when I accidentally exported a replay. I had to kill the process because it took too long to finish and could not close the window normally. Some way to cancel the export would be nice.
2. I had no controller issue.
3. I played with the two sticks setting and thought it was a clever and mostly intuitive way to control the gymnast, though I had similar thoughts as Kakeb. I'm definitely curious about your ideas about this. About the physics, I think they're fine, but also think it would be worth experimenting with slower speed and maybe a more rigid gymnast. I feel he wobbles a lot wich makes him more unpredictable.
I would have prefered if the slow down feature was a toggle instead of a countdown. As it is now, I have to watch my slow down meter carefully to not be surprised by a return to full speed or accidentally lock myself into constant slow motion.
4. You did a great job with the current levels. I like the variety and the difficulty. I also really hope you keep your levels as short as they are now in the final game. I think it's the key to making your game fun instead of frustrating. It makes it almost painless to restart multiple times. I do have some comments on specific levels though:
In "Time the Drops", I found the last "jump" annoying. The sudden acceleration of the bottom bar sometimes made the guy move uncontrollably and stops only for a moment not giving me time to slow down or aim. Every time I successfully made this jump I attribute to luck.
My least liked level is "Slide Along". I have no idea what is the correct way to make the jump from the rail to the last bar and I barely know how to traverse the rails. There's probably a trick but I cannot figure it out.
In "Rope Traverse" and "Transfer Variety", sometimes ropes make "knots" wich aren't realistic or fun to undo. Also when I let go of a rope, the guy sometimes regrabs it and kills my trajectory. Maybe disable grabbing as long as RB is pressed down?
5. I still have to try the level editor. No comment at the moment!
6. I think this is the kind of game that gets more fun the better you are at it, but yes I did have fun :)
That's all I have to say for now! Keep in mind that I do like the game and only played for a few hours :)