The warranty. The warranty makes this a killer deal.
Generally these refurbs are 90 day warranties, and save you around 100 dollars on a new one.
This is no different. It'll save you around 100 but it has a three year extended warranty that, judging on site reviews, they actually honor.
Site reviews are very good. I personally had questions answered within the hour by email.
Refurb questions: Personally I don't like refurbs with signs of use. They replied that all units are factory refurbished and as new.
Warranty questions: They have stated to me via email that if for some reason they cannot find a replacement, they will refund if the unit is in warranty.
Free shipping. Yay.