You're not alone. I gravitated back and forth between PW/B and SS/B right up 'til Mini started building my car. And like you I was concerned on seeing some photos that made it look rather drab. So I searched out every picture and every comment on this color I could find. The comments are what put my mind to rest. In all my reading, every opinion expressed regarding this color was glowing. I liked the one that said, (paraphrasing) this car will probably pass up the dark silver as the coolest color seen on the Mini Cooper. Another likened the color to a good champaign. So, I've come to the conclusion that sparkling silver only photographs accurately under strong light conditions.
Let's both of us post follow-ups once we receive our cars. Maybe we can put some other doubting minds at ease (assuming we're as impressed with this color as we hope we'll be - and I have every reason to believe we will). Maybe we should start a sparkling silver support group :-) .