Eh, you get used to the physics. They're definitely not perfect, but the controls have a learning curve. I have no problem playing JSR now compared to when I first played it. You eventually play it enough times and you master the controls.
The level design however, is perfect. Maybe you don't like timed levels where you have to memorize level layout and have a plan of attack, but that's what makes JSR's level design so great. Learning the levels, executing a plan (green tags versus red tags for points or for time), and getting so good that you can get a Jet ranking on every level is the meat and potatoes of JSR. It's arcade-y gameplay that remains fun no matter how many times you do it.
