Based on its 9% drop in share price following the announcement of fiscal 2015 second-quarter earnings, Microsoft (NASDAQ:MSFT) clearly reported some disappointing numbers. How else to explain investors stampeding toward the exit? And ex-shareholders aren't alone in vilifying Microsoft following its earnings news: a laundry list of industry pundits have lowered their price targets on the stock, citing earnings that "came in below analyst estimates."

All the negativity surrounding Microsoft begs the question: what's an investor to do? A couple things. One, as noted in a recent Fool article leading up to Microsoft's earnings announcement, focus on what really matters. Microsoft is in the midst of a significant transition, yet many investors and analysts continue to measure results based on its past. Second, recognize the sell-off for what it is: a great opportunity.

The good news
On the upside, Microsoft enjoyed an 8% year-over-year jump in total revenue, driven in part by increases in its devices and consumer division. And not just any increases, but improvements in one of Microsoft CEO Satya Nadella's mobile-first, cloud-first pillars. Surface tablet revenue was up 24% from last year, to $1.1 billion, thanks to strong Surface Pro 3 sales.

Nadella's mobile strategy goes well beyond hardware sales, of course, including making Office 365 available for Android and iOS mobile device users. But the success of Surface Pro 3 is still crucial to Microsoft's transition, as are reasonably priced smartphones in emerging markets. Toward that end, Microsoft sold 50.2 million mobile phones in the quarter, down from last year's 63.4 million units. Bad news, right? Not necessarily. Over 10 million of fiscal 2015 second-quarter phones sales were of the Lumia smartphone variety, up from about 8 million last year.

Perhaps the most critical aspect of Microsoft's financial results is cloud revenue. It's no secret Nadella is going all-in with this business. At this relatively early stage in Microsoft's cloud efforts, double-digit growth simply isn't enough. Thankfully, Microsoft didn't disappoint in reporting a 114% jump in cloud sales compared to the year-ago period, which puts it on pace to generate a whopping $5.5 billion annually.

To put that into perspective, fellow industry behemoth IBM (NYSE:IBM) is also diving headlong into the cloud, and it, too, is moving in the right direction after recently reporting strong revenue growth in this segment. At an annual run rate of $3.5 billion, IBM is among the leaders in cloud-related sales. But Microsoft isn't just leading the cloud pack, it's pulling away from IBM and other upstarts.

The often-overlooked Bing search results also pleasantly surprised, and now account for nearly 20% of the U.S. search market, which in turn lifted ad revenue by 23%from last year. Toss in a ridiculously strong balance sheet that boasts over $90 billion in cash and equivalents, along with plans to complete its $40 billion share buyback plan by the end of 2016, and Microsoft's quarter doesn't seem quite as bad as the naysayers suggest.

What's not to love?
With Microsoft delivering in key areas -- namely cloud and mobile sales -- what's the problem? Microsoft bears will point to net earnings per share dropping 9% from a year ago, from $0.78 to $0.71, as a significant shortcoming. However, on an apples-to-apples basis -- in other words, after removing one-time expenses including costs related to the purchase of Nokia's handset division and a tax reporting adjustment -- Microsoft would have generated $0.77 per share in earnings. That's not an improvement from the year-ago quarter, but it's hardly a glaring concern, either.

Xbox One sales also dropped to 6.6 million units from 7.4 million in the prior year. Finally, a 13% drop in Windows-related revenue took many by surprise, and rightfully so. Microsoft puts much of the blame on a weak business PC market and low-cost licenses to students; with the rollout of a free (at least for the first year) Windows 10 on the horizon, the division will continue to be pressured in the near term.

Was Microsoft's quarter good, or bad, across the board? No, on both counts. However, for mid- to long-term investors it couldn't have gone any better. Why? Because Microsoft stock just went on sale, and even many of the "lowered" analyst estimates still have price targets 20% and 25% higher than its current share price. The worst mistake an investor could make right now would be not to add Microsoft to his or her portfolio.