Is it any surprise that Snapchat now supports ads? It was only a matter of time really. The time-sensitive, image-based social app is a hit among consumers, and even marketers have found creative ways to integrate it into their campaigns. That kind of popularity doesn’t go unnoticed by brands looking to reach wider audiences.

Following in the footsteps of other social apps, like Instagram, Snapchat recently introduced its first piece of sponsored content. The ad debuted in October and promoted Universal Pictures’ upcoming horror film Ouija. The studio said that its 20-second trailer amassed views “in the millions.”

That’s pretty impressive for a piece of disappearing content. But before you start designing your own disappearing Snapchat ad campaign, here are a few important details to consider.

Views Aren’t Guaranteed

Part of the appeal of Snapchat is that users only have one chance to view a Snap. This requires the viewer to give the piece of content his or her full attention and be ready to engage instantly. Snapchat ads follow pretty much the same structure.

Unlike ads on Twitter or Facebook, sponsored content on Snapchat isn’t displayed in personal communications or searches. Rather, it’s added to Recent Updates and members are given the choice of whether they want to view it or not.

Once added, the ad disappears after it has been watched or within 24 hours of its arrival. This is worth repeating: after 24 hours, the ad will disappear whether 10 or 10,000 people chose to watch it. There’s no way to predict reach since it’s left completely up to the viewer’s discretion.

Where services like Instagram Video and Vine can be watched at any time, as many times as the viewer likes, Snapchat ads have a very short half-life and no guarantee that anyone will watch.

Limited Demographics and Data

Snapchat is focused on delivering an ad experience that’s “fun and informative,” not “creepy and targeted.” What does this mean for marketers? Snapchat ads are currently one-size-fits-all. While the app can deliver significant followers and shares, it doesn’t share any demographic-targeting data, so there’s no way to target the ad so it reaches specific subsets of users.

The silver lining here is that Snapchat’s user base is pretty much dominated by teens and millennials. In July 2014, the company reported that 18- to 24-year-olds make up 30 percent of its user base, while nearly half (48 percent) are 25 years old and up. And a vast majority of its users are based in the U.S. or Europe.

If you’re looking to reach younger generations in the U.S. and Europe, flying blind on Snapchat isn’t such a big risk. But if you’re hoping your ad reaches engineering students on the verge of graduation in Boston, who just purchased a new laptop, you’re better off securing advertising that supports robust targeting.

At this time, it’s not clear whether you’ll receive any sort of demographic data from Snapchat about the members who interact with your ad.

Not a Native Experience

From a technical standpoint, ads operate pretty much the same way regular Snaps do. Visually, however, there’s a big difference. Rather than have an ad look similar to a Snap created by a regular user — like a photo overlaid with an illustration — the first ad to run was a video.

According to Doug Neil, Universal Pictures’ executive VP of digital marketing, the studio edited the Ouija trailer for the platform so the scenes looked stitched together like a Snapchat story. Aside from this change, the move trailer could just as easily be run as a YouTube pre-roll ad or Facebook auto-play video.

That’s not necessarily a bad thing, especially because members have to opt in to interact with ads. Blending in with other content might do more harm than good when it comes to engagement. You want your ads to stand out. While the non-native ad approach might not work well on other platforms, it could very likely work in favor of advertisers on Snapchat.

But keep in mind that like on other social platforms, new features — especially ad related — aren’t always welcome. There was some pushback from Snapchat members on Twitter regarding the new ads. Not everyone is happy to see them, but fortunately the opt-in nature of the ads should help with the transition.

Overall, Universal’s first ad experience on Snapchat was a success:

“The people who watched the ad were ones that pressed to play so they were focused on actually viewing the content. As it turns out there were a number of people who screen captured it and it’s actually moved beyond the Snapchat window. But our goal was to get exposure in Snapchat and that was accomplished.” – Doug Neil

It stands to reason that other movie studios could find similar success advertising in the app. However, for most brands, success on Snapchat will depend heavily on your product, approach, audience, and overall goals.