1-) So many likes to follow, they are normally ignored as-it-happens
2-) A "Like" does not show up on FB stream, but more so on side bar as-it-happens
3-) A "Check in" shows up on stream with a link to FB page and a map image for location
4-) Most who "check in", will probably "Like" anyway, but business will not be seen as begging for Likes
5-) The "check-in" performs much more like an advertisement on the customer's FB stream, since it shows up as a post
6-) "Check-ins" encourages new visitors (discovery) much more rapidly
7-) Encourages conversation amongst friends with the business as the heading!
Check in to any business via your cell phone next time you are in a store, and you may realize the real difference it displays on your timeline.