"Receive five (5) days of Early Access* if you Pre-Order by January 7, 2013 11:59PM CT // 5:59AM GMT!"It's currently December 18th, so that gives you three weeks to decide... on paying in full in advance for an expansion scheduled to release in "Spring 2013". As Syp notes, the fourth bullet point on why you should buy the expansion is that more information is "coming soon", so even Bioware acknowledges that relevant information for your purchasing decision is not yet available.
Technically speaking, the ad does NOT promise that people who pre-order after the deadline will not ALSO receive the early access. If so, it is merely badly misleading, trying to trick players into buying now through a false deadline. That's the good scenario. The bad scenario is that four months from now you log in and your guild is split into haves and have nots because some people failed to click buy fast enough.
Paid early access programs are ubiquitous for new MMO launches but rare for paid expansions - offhand, I recall one year where SOE gave retailers a one-week exclusive on an EQ2 expansion, in the process screwing over international players who could not physically obtain a box. There have been a few games that have temporarily shut off additional sales because their servers could not accommodate more customers. I know of no situation in which a live MMO with adequate server capacity has divided the community in order to teach them an object lesson that they should be paying in full for content before the details are released and months before it is ready.
Honestly, it makes so little sense that I'm assuming the marketing people are just lying through their teeth when they say there's a deadline in three weeks. Is that really where you want your relationship with your MMO provider to be? Is this a business practice you really want to support? If this really is a fair price for a quality product (which is possible - though unknown at this early date), did they need to resort to this type of strong-arm hard-sell?