Oooh... I dunno if I'm good enough to critique, but I recon there are a few fractions of a second bits that could be improved upon....
interesting start... don't know if it is faster to pop up like that than rapid-fire braking.
slightly long pause in the top left corner.
There's something clever to be done in not over-jumping too far to the top-right platform.
really caution slow-down in the bottom right corner...? (but then who isn't towards the end of a nice run!)
I love these 50 second levels - there is a real reticence to go at full speed, but often great rewards in a rapid smooth run.
There are a few spots for improvement. The bottom right i did a bit slow. If you get a perfect drop there you dont really neeed to slow down, but ive only gotten it perfect 1 time.
Maybe you could brake off the first platform at the top, bounce off the ground, cablecar the second platform at the top, then brake to drop down to get the next flag. It looks plausible but very difficult to me.