Rating: 1 out of 5
Why? First of all, It does more damage to the phone than it does good.
1. One of the prongs that holds it on catches the keyboard every time you open or close the phone. This causes a scratch on the keyboard.

2. It doesn't "hug" the phone, so it can jiggle around by a couple of nanometers, but this is enough to cause a horrible line all around the edge of the screen.

(Note: It goes all around the entire screen, just only that part shows in the pic)
3. Extremely difficult to get off, and it looks like it might pop off the keyboard every time you try. Also, if you don't want that to happen, and leave a couple of prongs on, and slide it, it messes up the call and end keys. (Human error, I know)

I would only recommend this if you are very prone to dropping your phone, and don't mind a couple of scratches. Either way, I would deeply recommend a silicon case. Even though it attracts a lot of dust and lint, it's the best way to protect your phone. (Screen protector is still probably the most useful.)
I hope this review helps.