Thoroughly enjoyable and I'm looking forward to new levels.
When first introduced to the sparkly portals in the tutorial world they make sense. You then play through all of world 1 without encountering them.
Level 2-1 they are re-introduced but with the exception that you may get the impression that they are suddenly a bad thing. When I dropped into the portal I had the monster drop on my head. Everything happens very quickly (drop into portal, zap, monster kills and respawn) and I just got the impression that suddenly - in this world -portals are bad and zap you or something.
Level 2-3 did correct that impression although it took me far too long trying to wall jump up until I finally missed a jump instead of hitting a flame.
The only other thing was the timed platforms could linger 10 milliseconds longer but that's just a personal preference.
Keep up the great work :)