To sum it up in my opinion, it looks to me like you're trying to complete the game very quickly, rather than perfectly. I'm not going to deny it, you progress through the game extremely quickly, ESPECIALLY for the amount of rerecords you use. But I guess my two main problems are that either a) often I feel like you either don't use slow motion enough, or if you intend to do something and then it didn't work out, you don't mind, and keep going. If you did so well with so few rerecords in a run as long as that at a game as fast as that, I would like to see what you could do using more rerecords. For specific examples:
The most consistent, noticeable thing would be that you don't use your rocket boost the instant that it's fully charged. I'm not going to deny it, it is used so often that doing so will be a huge pain. But with the fast pace the game takes, this is necessary for it to look better. I'm sure sometimes you want to keep the charge for a moment so you can get a better angle at your target, but for something like boss fights it's crucial.
The first time I really noticed the thing where you intend to do something and it doesn't work out but you keep going, is with those rows of mines that you boost through and explode on your way. Boosting through them neither gains nor loses you any time, but you did so because it looked good, which is always greatly appreciated. So you were obviously going to the effort to hit every mine, but at one row of mines you missed one. I'm not sure if you tried several times after that or what, but it looked like it could definitely be done.
Another example of the above is missed shots. There are very many missed shots on the overhead, self scrolling flying level, obviously not including the side-bullets or the shots intended to be in sync with the music(which I always appreciate and was a nice touch). It's the ones that are intended to hit something, but don't that I speak of. Another prime example is the final boss fight. As you're jumping to hit the rings, you make one extra slice on most jumps which never comes in contact with anything. Also, this was the only part of the run which was actually boring.
edit: With regards to the above examples, I'm not saying they were the only ones in which those kinds of things happened, I'm just trying to help you know what I mean.
A last thing is, is it possible that the boxer AI is more complex than that, and that you can optimize the time in which he is vulnerable? If not, and if the crystal boss is optimized as well in terms of time, then those two are indeed fine. edit: other boss fights which could benefit from more optimized AI controlling include the dragon in (I think) the forest, and the arch-nemesis battle soon after.
Good run overall, but there are indeed changes to make throughout, and as I said if you produced that with so few rerecords, you could do a lot more with a whole bunch of rerecords. Looking forward to any possible future versions!