Take this recent example from Vodafone.

Aside from the obvious downsides (user doesn't know where the link will take them, if it's compatible, link looks like gobbledegook, etc) there is a rather more interesting issue.

Goo.gl - along with many other URL shortners - give everyone access to your statistics.

Visiting http://goo.gl/NdVGI+ will let you see everything.

I don't know how many messages were sent out, so it's hard to calculate a response rate.

From the map, I can see the two target areas were UK and (unsurprisingly) Greece. There are a few hits in other countries - that could just be people connecting via WiFi networks routed through that country.

There are also a few hits from iPhones - suggesting either the targeting wasn't accurate, or people are spoofing the iOS user agent.

Still, it's an interesting insight into Vodafone's marketing.