You will definitely notice the difference between the screen with a shield and one without. I much prefer the screen without the shield, but I think the excellent protection it provides is worth the trade-off. IMO it makes typing a little easier as well.
As for the back, I really liked the way it made my phone feel. It doesn't add any noticeable bulk, and it keeps the phone from sliding out of your hands without sticking to your pockets too badly (like rubberized covers do).
Overall I would say it feels good in your hand, you just won't find your fingers gliding over the screen so nicely anymore.