Gartner gave much of the credit to improved budget phones ($150 or less) from manufacturers that thrive on them, such as Huawei and Xiaomi. Samsung did have the launch of the S9 to its advantage, but that wasn't enough to prevent Chinese rivals from making a dent in its mid-tier sales. And while Apple did return to growth, it still "struggled" to convince many users to upgrade to its latest premium devices. The biggest winner was Xiaomi -- its sales more than doubled thanks to a revamped lineup and "aggressive" pricing.

Whether or not happy days are here to stay is another matter. Samsung will have the benefit of a first full quarter of S9 sales, but the middle of the year can be sluggish as buyers wait for the big updates that tend to come in the late summer and fall. Phone makers may just have to cross their fingers and hope that the dark times are over.