Hey there! Thank you so much for the feedback, it means a lot.
It's a work in progress, we still need to balance many things out, so any feedback is welcome. When you say slower, what do you mean? The movement? The cooldowns? The progression? The play time?
We'll release new arenas, with the goal of having an easier arena at the start, then you can unlock harder arenas by achieving a certain high score. I hope that will help with the learning curve, but you can also check out this update's gameplay so you can get a feeling for it!