I have been tasked with building alongside another developer a mobile app. This is not my first mobile app, but it is the first app that I have worked on that uses Flutter.
Flutter is made for developing 2D web apps quickly and does it well. It's very easy to get setup and at is easy to start building your first app. Without having to install any dependencies outside of what the basic flutter project gives you, we were able to create a pretty functional POC (Proof of Concept) that performed really well on both Android and IOS devices.
I also liked that if you were looking for help in a topic, even an outdated version of Flutter's code was helpful and didn't send you trying to find exact versions of the platform. This is something I have experienced with React Native as-well-as Angular development in general. So, I am glad to see that they are making good positive changes without breaking everything between iterations.
Working with Material Design just makes things simple. This isn't going to be for everyone. I can fully understand if you want your app to be 100% customized by you without any input from someone else. But, Material Design is so customizable that it doesn't just feel like another Google App with paint on it. You can literally make your app look just about any way you want without having to worry about coding all of your widgets from the ground up.
I'm no expert at flutter yet, but I hope to become one one day. I think that this will gain traction and be a very great addition to companies who need to build mobile apps that are mostly CRUD (Create, Read, Update, Delete) forms. So far, I like how it makes designing on Android and IOS easy, it provides me and my client the necessary tools to complete their job, and it is fun to work with.
I think there are a range of ways to build an app, but I do think for a specific use case flutter can definitely be the best way to build an app. You'll have to decide if it is best for your project on your own because each project can be a good fit with different technology. Where I see it being extremely valuable is if you need an app for both Android and IOS devices and you want to build it quickly without having to worry about maintaining a UI Library. Having Material Design built in and theming options available, makes it really quick and easy to get an app looking like your own and still not having to custom build every widget.