The transaction confirmation times are pretty brutal. Pretty much casual use of Bitcoin (like buying a hotdog on the street) is very hard to do because of this. Sure, it might be a low value item, but people will exploit anything they can. The only time I think people would buy something with Bitcoin that wouldn't be any less convenient than FIAT is big value items like cars (where there would be tons of paperwork to do anyway) and online shopping, and of course the block chain issue isn't helping any of this.