For brick and mortar businesses simply accepting it isn't a big deal, but the big hurdle for staff and operations would be the point of sale system they use. Next would be a lack of understanding/unwillingness to understand that they can use bitcoin as a network, without necessarily getting any exposure to the asset itself. Working with bigger companies means going up the chain of command, which is time consuming.

For Ecommerce, businesses using systems that have very limited API access can be a show-stopper, making it very difficult to incorporate it at all.