For several years now, the Nike+ Running app has been an essential download and companion for millions of people trying to keep fit and improve their health. It's got between 10 million and 50 million installs on Google Play, and I'd bet on it being even more successful on iOS. But recently (and very randomly), Nike decided to take a gamble and overhaul an immensely popular smartphone app from scratch. It's now called Nike+ Run Club and, well, let's just say that the reception hasn't been very positive so far.

Despite a tagline claiming the new version was made "for runners, by runners," many old Nike+ users are livid with the sudden switch and the loss of functionality and features that made Nike+ Running feel so vital. As a result, the new Nike+ Run Club app has plummeted to a 2-star review average among iPhone users; that's actually up from the 1.5-star rating it showed immediately after the redesign. You know it's rough when Windows 8 burns start getting tossed around.

Sure, the app's core functions remain: it'll track the distance, pace, and GPS route of your runs. But in the process of revamping everything — again, for no obvious reason — Nike stripped out features that actually motivated some people like trophies and challenge programs between friends. Sharing your progress to Facebook and other social media is also more difficult; first you've got to share your run with Nike's own rando stream and then share it out again to other destinations. These are annoyances that just didn't exist before.

And in place of the old, competitive community challenges are... hashtags. Thankfully you can still access leaderboards between friends and people you actually know to see who's racking up the most miles. Personalized coaching is still a fundamental part of Nike+ Run Club as well, but a lot of users have had their in-progress marathon training disrupted or erased completely due to the update.

To compensate, Nike has a solution: PDFs. The company has made PDFs available containing each of Nike+ Running's coaching plans for all fitness levels. Better than nothing at all, I guess.

Still, take a look at the Nike+ Run Club Facebook page and you'll see a stream of complaints beneath each and every status update. Same thing if you head over to Google Play or the App Store. There's some praise mixed in here and there about the app's new look, but for the most part it's page after page of "you've ruined an app I loved." Brutal.

To be fair, Nike's team seems to be working overtime in response to the swell of criticism. Nearly every comment on Facebook gets a reply from the company directly, and just today, the Nike+ Run Club app on iOS was updated to restore support for profile pictures and tagging shoes to track mileage. I still miss the "notes" section though, which I regularly used to write down treadmill incline settings at the gym. It's frustrating when little things like that just vanish. But Nike is definitely hearing your feedback, cliché as it sounds.

This is always the danger when a company makes big changes to a popular app — one that millions of people open every day. "Bring the old version back" is probably not the overwhelming response that Nike was aiming for, unfortunately. Is everything ruined? For a lot of people, probably not. I doubt I'll quit using it. But for some, Nike is giving Runkeeper, Strava, and other running apps one heck of an opening.