I sold my iPad OG and iPod Touch (3rd gen) to pick up the Prime. I haven't looked back. Reason number one for me, I'm tired of the way Apple does business, suing the pants off anyone who gets in their way for instance. Second, I have an Android phone and buying apps one time, is a major plus versus buying it in iTunes then in Android Market Google Play. I also really like the customization/personalization you can do with Android out of the box, with iOS, you have to jailbreak to do anything fancy at all. Now for the Prime specifically... THE POWER!!!! Not to mention the beautiful and TOUGH Gorilla Glass screen and awesome keyboard dock should you decide to buy that accessory. With the dock, connection options seem endless, between cabled LAN (via USB adapter), wireless mouse and game controllers. And you don't need to use up your bluetooth connection to have a physical keyboard. I love my Prime and have NO regrets in moving away from Apple to get it.
**Edit... oh yeah, as stated above, apparently you can play .m4v files with the stock media player. But I did look in Google Play and 3rd party apps will definitely let you do it... for free!