Thanks for playing and for your great feedback :)
I agree with all you said, and will make sure to improve them in the future!
I actually planned on making the boss level be based on the portals as well but didn't have enough time to design the levels properly as I had to do it myself at the last day.
I'll have to make sure the aiming mechanic is clearly explained so there's no confusion, and the mechanics more used in even all levels.