I plan to use it for both. I guess we'll see how it goes. I am not sure how useful it will be for comparison pricing, since I have a few preferred sites for that purpose.
I use it when I go shopping for electronics, I prefer brick and mortar stores to online shopping, though if newegg has a fantastic deal, anyhow I digress. But if I'm going to but something I fire up shop savvy scan the bar code last time it saved me 40 bucks on a blu ray player since the place I shop has price matching I showed the sales rep it was cheaper at another store and he matched it. Comes in handy alot
I find it most useful for getting reviews on products when I am out running errands. Just yesterday my wife was looking for new ear-buds, and rather than simply choosing them by brand or price, we scanned a few different products and checked reviews.
I've saved on x mas gifts , a tv, many more but saved well over $400.00 on those alone... some stores will say they cant price match... no biggie, drive down the street or ask for a cooler manager... someone will match!