I tried 303 protectant today, I was a little underwhelmed by it. It looked great on the dash, but on the insides of the doors and the plastic moulding on the outsides of the doors it looked really uneven.
Give it some time, more applications.
I also don't spray it on the plastic and then wipe, I wet my cloth and then wipe it on.
303 actually repairs the surface of the plastic, it causes the little microscopic shards of roughness to lay back down
over time.
So, soon enough your interior begins to look better. You may not notice as you are the one doing it but someone who saw your vehicle last year, went away to college, got drunk at Spring Break and served a short jail sentence for public indecency, then came back and bummed a ride from you to her probation officer would notice.
"Hey, this interior looks better than before my life fell of the rails!" she would say.
Just give it some time, don't give up.