Google released a video calling app Tuesday to compete with the likes of Apple's FaceTime.

What it looks like once you're in a Duo video call. Google

The tech giant first announced the app, Google Duo, at Google IO in May. It's a simple, one-to-one messaging app that doesn't come with a lot of fanfare — you simply scroll through your contacts to see who has the app, click, and connect. But as Nick Fox, vice president of Google's communications division, told Business Insider, that was intentional.

"I’d say if there’s kind of one North Star, it was making it super, super simple," Fox said. "It’s kind of drop dead simple. And we’re kind of maniacal about it — cutting features, turning away features, and making it really, really easy."

Google Duo is entering a crowded space. Apple, Snapchat, and Facebook all offer video-calling services for consumers. That's not to mention Skype and even Google Hangouts. So if it doesn't have any noticeably edgy or cool features, why download it?

Fox argues there are two features that set it apart from its competitors: it's designed specifically for mobile and it's a cross-platform product, meaning you can download it on any device.

"We do believe that video calling should work for everyone," he said. "It shouldn't’t be limited to one OS. It should work across Android and iOS."

That could arguably be a jab at FaceTime, which can only be used on iOS devices. But that doesn't really address other competitive apps like Snapchat, Facebook, or, yes, even Skype's mobile app. People who want to make video calls to those with different phones already have an app that will get them there.

Google was sure to play up Duo's Knock-Knock feature at IO. The video shows a live video preview of the person calling you before you even pick up the video call. That way, the person on the other end can start waving or show you were they are before you even pick up.

It's actually a really cute feature, and I could see it being fun to use if you want to tease exciting news like concert tickets you got for your friend.

However, it doesn't work on iOS devices. Fox said that's because Apple doesn't allow third-party developers to access the lock screen, so instead a notification shows when a video call is coming.

"So you don’t really get the full Knock-Knock experience on the iPhone until they give us the ability to do it," he said.

This is unfortunate considering Knock-Knock is Google Duo's most interesting and unique feature. For some, the limitation may make it that much harder to justify downloading yet another app when it functions so similarly to what's already out there.

The last distinguishing feature Duo is said to offer is that it provides a video-calling experience even in areas of poor service. As Fox explained:

"When you’re in the call, if you’re on a really high-quality WiFi network or great LTE network, it’ll be in beautiful HD, great video, great audio. But as you get to more impaired networks, [the quality] will degrade gracefully from HD to maybe standard definition, and if you get to a network that can’t support video, it will again degrade to audio only."

I gave it a shot with Business Insider's Jillian D'Onfro. First we took it from the office, to LTE, and lastly the elevator.

In the office, the quality was clear, but the picture was a bit foggy. Still, totally acceptable by my standards for a video call.

Once we got to LTE, the video became pixelated. We got a warning that we were entering an area of weaker service, but it didn't look great.

In the elevator the video call cut off entirely. That's something I'd expect with any video-calling app, but I didn't exactly feel it degraded "gracefully."

Overall, Google Duo is a fine app, but it will probably appeal a lot more to Android users than iPhone users.