Hi there, just went through this pack and I have a few thoughts I'd like to share.
I'll start with Act 1. It's always interesting to see Emerald Hunt stages, but I'm not a big fan of how it was implemented here. The best Emerald Hunt stages, in my opinion, have varied terrain and hidden areas to hide the Emeralds in (when I say hidden, I don't mean impossible to find for the record, just something you need to pay attention to find).
This level, however, is essentially just a flat, large box with a few very minor obstacles, and Emerald Pieces being placed in somewhat haphazardly. Many of these pose little challenge, such as the box with the Spring Shells for example. I would like to point out however, one can become unobtainable as Sonic if the player is not paying close enough attention. There is an Emerald spawn on a little tower in the corner of the map that is only accessible by the Spring Shell roaming near it. If you destroy the Spring Shell there seems to be no way back up, even with the Whirlwind Shield provided in another platforming segment. In the future, I would make sure to pay closer attention to things like these to avoid the frustration that comes with having to restart a level.
With that said, let's move on to Act 2. I think this is a step up from Act 1, but it still has a variety of problems. The terrain being completely flat is arguably an even worse problem here, as the goal of this is to simply get to the end. The enemies place around the level are not suitable obstacles, and that combined with the aforementioned flat terrain problem makes this stage incredibly easy to blaze through. As Sonic, I was able to get a time below 30 seconds on my first try. While sometimes it can be exhilarating to get through an Act that fast, the lack of challenge in the level makes it feel like it was not earned.
I do not really have much to say about Act 3, aside from the fact it seems to be missing rings. I do not think a Pity Shield that spawns once in the middle of the map is a good substitute for good ol' fashioned rings. I also generally dislike when vanilla bosses are reused in map packs, but that's more of a personal preference thing.
Overall, I think this level pack is... not great. But that just means there's a lot of room for improvement, and you will naturally get better as you learn more about mapping! I could see you making some genuinely great stuff in the future, so please don't get discouraged, and keep at it!