Well, i got this battery today as i wasn't too happy about running out of juice before the day's end as often happened with the stock battery. I charged it up and calibrated my galaxy to it and so far it has held it's charge rather well. I'm expecting to go at least a full 24 hours without recharging it - so fingers crossed.
Material wise, the supplied back is no better or worse than the original. It snapped on without much fuss, although the "snap" wasn't very audible/solid, so i had it make sure it was on properly by gently pressing around the sides and corners. Fit and finish seem alright, with the cover fitting perfectly around the galaxy's contours - no barbs or imperfect surfaces to be seen.
It comes in glossy black and all in all, if i was unfamiliar with this phone, i would have not thought of the cover to be anything but standard stock, really. It complements the phone nicely, IMHO, despite making it look like...a brick. It's now easier to hold for calls.
My only two complaints thus far are: 1) i cannot use my beloved leather flip case any more as this beast ceased fit and 2) the camera now suffers from mild vignetting (tunnel vision) because it has to peer though a longish hole in the thick case. I would have thought this could actually be compared to using a lens hood on a regular camera, thereby protecting from the sun, etc, and be beneficial but since the black plastic is shiny, it sometimes causes reflection artifacts in the pictures. I'm considering modifying the case by painting the interior of the peephole matte black to eliminate this.
Now going to try and find a suitable case for this beast or resort to using socks again.