I blorblieved and finished the game but I didn't find (or search for) the secret levels.
It's a little annoying how long it takes to slow down, but once you get in the habit of committing to a sequence of jumps without stopping it's fine.
The floating platform+trampoline level could have used an extra checkpoint or two imo.
This is personal preference but when I play sidescroller games I bind the jump to like K or J, I switched to a controller and it was okay no problem there.
There was a couple of times where I pressed the jump button a split second before blorb landed on a platform and he just walked into the abyss, checking to see if the jump button is pressed when blorb lands could make jumping sequences a little smoother.
Over all nothing that makes blorb stand out as a platformer, but what's there is competent and I had fun finishing it.