Microsoft’s (MSFT) debut tablet isn’t shaping up to be the runaway success story the company was likely hoping for. New estimates from UBS analyst Brent Thrill suggest Microsoft only sold 1 million Surface tablets during the holiday quarter. The news could represent a setback for Microsoft’s Windows RT tablet operating system, as a number of PC vendors are reportedly using the Surface as a gauge to determine whether or not they should embrace the new platform. The only good news, perhaps, is that the analyst’s Surface estimate is slightly better than earlier projections from Detwiler Fenton suggesting Surface sales wouldn’t even reach 1 million units in the fourth quarter. In his note to clients, which was picked up by Business Insider on Monday, Thrill also trimmed his revenue and EPS estimates for Microsoft’s second fiscal quarter to $21.3 billion and $0.76, respectively.