My DC trip was super-last minute. And ridiculously so, since Evan and I had long been planning to go away that weekend.

But we’d gotten so caught up in planning that we ended up not planning anything. For weeks, we debated whether we should do DC, or a Jersey beach town, or maybe Philly or some other place in between NYC and DC. We finally decided to do DC on Friday morning—i.e. the day before we were to go wherever we were going.

That meant that we weren’t able to book a hotel in advance. But it seemed like an opportunity to test out Hotel Tonight, an app I’ve been curious about.

Hotel Tonight’s premise is that each night, hotels have vacant rooms. Instead of letting them be missed opportunities for profit, why not offer them up at discounted rates for people who want/need last minute places?

The catch is that you can only book hotels the day of. And you don’t know what hotels and rates will be available until that day.

Hotel Tonight doesn’t release the day’s deals until 9 am. After that, you can search for your destination city and enter whether you need a hotel for one to five nights. Then your results come up.

I spent some time in the app on Friday, to see if we’d want to use it the following day. I was impressed with the slick, user-friendly interface. Each hotel option has a nice photo and its location, price for the night and, in most cases, the normal rate. Helpfully, hotels are also classified as “Hip,” “Luxe,” “Solid” or “Basic.”

Hotel detail pages include many more photos, both from the hotel and other users; its user-rating; its location plotted on a map; and other basics facts, like room size and Wifi costs.

I especially liked Hotel Tonight’s “Why We Like It” notes, like: “Big, funky, chilled-out guest rooms with pops of pop art and Lite-Brite-esqie color” (for the Hotel Helix). They gave me a sense of the place, and tips on the hotel’s perks.

I felt that the app offered a good number of options (about a dozen), and prices seemed fair. Most were in the $99 to $150 range. High-end places in prime locations fell into that upper tier.

Hotels Tonight also has a weeklong forecast, where they note whether they expect to have many or few good deals.

Even though I was a little scared to wait until the morning of our trip to book, Evan and I decided to go for it. I figured the worst that could happen is that we wouldn’t find anything good, and end up at a hotelВ near the airport—not exactly the stuff of human hardship.

On Saturday morning, a little after 9, I opened the app. The Donovan House, a hotel I’d had my eye on, the previous day, was still an option. The price had gone up to $140 from $135. But that was still better than the rate that the hotel offered on its official site: $180.

Evan and I felt that $140 was reasonable for a hotel in a major city, in a prime location, with a roof deck pool, on a Saturday night. So we booked it.

We were very happy with our choice. Check-in was as smooth as if we’d booked through the hotel’s site.

Our room was nice…

…and we enjoyed hanging out at the pool.

While Hotel Tonight worked for us in this case, I don’t think I’d use it in many other scenarios. If we were staying somewhere for multiple nights—and planning in advance—we would have shopped around for a better deal, or booked an Airbnb.

But for a one-night, super-last minute trip to a city, I couldn’t have been happier. I’d definitely use Hotel Tonight again, in a similar situation.