Are you a bit disappointed with your new Apple iPhone 6 or Samsung Galaxy S6? If so, you're not alone. An analysis of more than 600,000 online reviews and comments posted by smartphone buyers during the past six months suggests consumers are jumping off the upgrade merry-go-round.\n"I call it 'upgrade fatigue,'" says John Feland, CEO of Argus Insights, the research firm that put together the report. "New phones are typically a vague improvement on old ones, with better cameras, memory, etc., but these small improvements are failing to create urgency for consumers to upgrade right away."\nOverall, consumer demand for smartphones appeared to slip by about 8 percent year over year, according to the\u00a0Argus survey.\nApple didn't getting quite as many glowing consumer reviews as it has in the past, but its smartphones still rate highly among consumers and iPhone 6 and 6 Plus sales remain strong. Samsung, though, is losing favor. "Consumers are losing interest in the smartphone market, and Samsung's flashy flagship phones could not reverse the trend," Argus says.\nUnlike research firms that measure actual sales and shipments, such as IDC or Gartner, Argus measures sentiment by analyzing online consumer comments. Overall, the company's database contains more than 7 million comments or reviews on about 9,000 products. Argus sells the data to companies that want to understand what consumers actually think about their products, but the company's research is not underwritten or sponsored by any of the manufacturers, according to Feland.\nArgus's negative take on Samsung lines up with the company's poor showing in the market. Samsung lost about 7 points of market share during the first quarter of this year, while Apple gained about 3 points,\u00a0according to IDC. Apple meanwhile vacuumed up more than 90 percent of all profits in the smartphone market, according to investment bank Canaccord Genuity, as cited by The Wall Street Journal.\nA burst of publicity and special offers following the release of the new Galaxy S6 phones gave Samsung a boost in what Feland calls "mind share," but it didn't last. Demand for the Galaxy S6 and S6 edge dropped shortly after their release.\nComments from consumers shed light on Samsung's problem. Many of them wrote things like, "the S6 isn't that much better than the S5," and they complained about poor battery life, trouble syncing, and wireless charging, Feland says. These concerns, and others, led buyers to return GS6 phones roughly twice as often as iPhone buyers.\nHowever, Apple customers also had gripes. One common complaint \u2014\u00a0poor call quality \u2014\u00a0turned out to be related to Sprint's network in certain areas where LTE service is not yet available. Sprint aside, consumers were mostly happy with call quality on the iPhone 6 and iPhone 6 Plus, and fewer people complained about poor battery life than Feland expected. "I think [Apple has] trained consumers to assume battery life won't be great, so they don't complain," he says.\nWindows Phones continue to slip in consumers' eyes, but that may be related to Microsoft's recent decision to cut loose 7,800 Nokia employees, a sign that the brand could become orphaned. \u00a0Overall, consumer reviews suggest people like their Windows Phones, though, especially the cameras, according to Feland.\nFeland and Argus have a point. Forking over $600 or more for a phone that's just a little bit better than the perfectly serviceable one in your pocket or purse doesn't make a lot of sense to the average consumer.