A shortened link will disappear when (not if) the shortening service disappears. If that is sooner than the site it was linking to disappeared, then it's a net negative for the web.
Link shortening services for the domain they live on are slightly less bad, since their lifespan is somewhat more likely to be equal to that of the destinations of the links (although it's still likely they'll live shorter).
That's ultimately what the argument comes down to: perspective. From the perspective of the poster, link shortening allows for a larger dissemination coupled with analytics. From the perspective of the web, link shortening creates a problem for the future (as they begin to break).
One downside could be the extra tracking and analytics URL shortening services provide, and people could see this as an invasion of their privacy. Personal belief is that there is so much tracking in the form of web analytics that goes on on the internet anyway that URL shortening is hardly making a difference. It has also provided some businesses like bit.ly with a way of generating revenue and creating jobs and for bloggers and people like me who do like to share what I find interesting on Twitter or Facebook with a way of seeing if anyone is actually reading what I have shared
Dead links are a fact of life on the web, but it's the idea that one domain-name going away would break links to thousands of different domains that unsettles people.
If you do like to see the full URL try, Chrome muse extension. It can shorten and expand URL's: https://chrome.google.com/extensions/detail/digfdjelalmeldlp...
Twitter is basically the same idea but applied to blog posts, and that is what created the market for short URLs.
The persistence issue is a big more complex since the validity of a link depends upon a third party. Shortened links are ephemeral like everything else on the web and may not always be a good choice.
- Used in a web app to share a link, or to brand the shareable link. i.e. shareable URL for each email newsletter promotion.
- Able to gather stats like a statcounter, who are the referrer, browsers, keywords, etc.