Up to you. The 4th gen iPad uses tempered glass. A little more rugged against minor scratches.
It comes down to your plans of keeping the iPad long-term or resale. Lots of people get screen protectors because they're thinking about resale value when the next iPad is released. Makes it easier to sell if the screen is immaculate.
As far as protection against drops. No screen protector will help there. Protection or not, if it's meant to crack, it will.
I decided to skip the screen protector. Not needed and the iPad feels better when it's bare. (I don't bother with a skin or case either)