I wonder if anyone who uses Amazon's Unbox service compares it to buying the DVDs. I just got a mail from Amazon suggesting I buy Star Trek episodes for $1.99 (although, being out of the US, I can't). I looked up the boxed set prices and Amazon sells all the original episodes for $176 or $2.23 an episode.

So for an extra 24¢ per episode you get a permanent physical copy - "If you uninstall or otherwise remove the Software, your ability to view all Digital Content you have downloaded to the Authorized Device will immediately and automatically terminate and we reserve the right to delete all Digital Content from that Authorized Device without notice to you" - that you can play on any DVD player, not just the 2 “authorised devices” - "As used in this Agreement, “Authorized Device” means any personal computer or portable media player meeting minimum system requirements that Amazon may establish from time to time or other device that Amazon may authorize from time to time. You may only view Digital Content on Authorized Devices" - and that doesn't call home to Amazon to say what and when you're watching - "Among other things, the Software will provide Amazon with information related to the Digital Content on your Authorized Device and your use of it and information regarding your Authorized Device and its interaction with the Service".

Amazon Unbox™ Terms of Use

If you have seen the end of Season 5 yet (unlike me), this page may be of interest. If you haven't seen the end (like me), you'll find it tells you it anyway...