Starter Edition = 14-day trial - time limit
The same restrictions (no trade, no auction house, no joining a guild, etc.) apply.
And if you can't access the AH, why even bother playing?
EDIT: Don't get me wrong, I wish Blizzard and Redeemed success, but I don't want people getting the wrong idea about the "Starter Edition" and claims that the game is "free to play to level 20." So much of the content that makes the game worth playing to so many (i.e. guilds) is unavailable that it will be useless to most as anything other than a system benchmark and a demo. Sure, you could play the trial for more than 14 days, but why would you?
EDIT#2: For anyone interested in trying out WoW, I'd recommend just waiting until the holiday season and watching for sales. The base WoW game (no expansions) has been $5 or $10 (I forget which) the last 2 years. For a low cost, you'd get to play the game for 30 days, experience the wonder of the auction house, and, most importantly, join Redeemed.

And it would be cheaper than buying the digital standard copy or whatever they're calling the paid upgrade to a regular account.