Starting with the build quality, the clear back piece seems solid and looks good but the polycarbonate side pieces feel pretty cheap. The unpainted interior sections aren't a big deal to me but the dented side piece on the exterior isn't a good thing. On a good note, all of the buttons and functions of the phone (sans the SIM card slot) are accessible with the case installed.
I appreciate that a screen protector is included, but as was shown here today, the case forces the screen protector to bubble around the edges.
As for overall protection, this case should protect your phone against scratches and minor bumps. I'm not so sure how it would handle a drop, as the side pieces could come lose and there is virtually no shock protection.
The SGP Ultra Slider Crystal Series case sells for $34.99, way more than it's worth in my opinion. For that price, you can pick up an OtterBox Commuter case, an all-around quality case that looks better and offers more protection than the SGP unit.
Thanks to SGP Store for supplying us with this review sample.