Agreed. Gestures based-app are like shortkey-based apps for your desktop: quick and useful once your learn it. But you have to learn it, which is too much of a hassle for something as simple as the weather. Gestures should be complementary to buttons.
Nevertheless, I haven't checked out this specific app. But in general, the above is my opinion on gesture based apps.
They are (almost) complementary to buttons - the buttons at the bottom control access to each "page" of info. The only hidden thing is the settings and forecast data, but the app gives you a quick short tutorial at the start to show you where they are, and it's "drag down", which most iOS users are used to now. You can drag down to reveal the forecast once, and it'll remember to keep it open, and the only things in the settings worth paying attention to are the themes, too, so you can pretty much do that once and then ignore them.
I bought the app myself and so far I love it. It's very pretty to look at and gives you enough info. It's obviously designed to be pretty, and not to be a detailed super accurate forecast of every last detail over the next decade, but it gives me enough info (temp, forecast, and if it'll rain), so I'm happy with it.
As for "enough of these silly weather apps", I'd rather have more than we need on the App Store. It gives people choice, and there are many other categories where there's only *one* app that does what I want, yet I'd really like more choice.