In one word, yes, with a qualifier. WiseGeek has done a brief writeup on the subject of using redirection services like TinyURL and SnipURL.
If your link is intended to be used for a short period of time, then redirection services are fine. If, however, you have a more permanent link that you want to post on a website, then you should realize that you are giving away valuable control to an external entity. If you want to use redirects for a more permanent or important application, make sure you trust the redirection service thoroughly.
Services like TinyURL and SnipURL have a solid track record and it’s not something to be overly concerned with. However, the writer does make some good points.