At first glance I dismissed it as there is no design tool but you soon come to realize that there little need for one as the Hot Reload is insanely good! The real beauty is that it produces native code on the target platform. Flutter's engine takes core technologies, Skia, a 2D graphics rendering
library, and Dart, a VM for a garbage-collected object-oriented language, and hosts them in a shell. Different platforms have different shells, for example there shells for Android and IOS. The shells implement platform-specific code such as communicating with IMEs (on-screen keyboards)
and the system's application lifecycle events. The Dart VM implements the normal Dart core libraries, plus an additional library called dart:ui to provide low-level access to Skia features and the shell. The shells can also communicate directly to Dart code via Platform Channels which bypass the engine. For more details see. The result is a solution that performs well on the target platform. Now it will not win the race against the native app but 60 FPS is not bad and in many case second best is the beat solution. Flutter is Open Source and I like to set breakpoints in the Flutter Code to a get a better understanding of what an operation is doing and to see some really high quality code.
The Flutter story excites me as we have a platform that addresses the UX for IOS, Android and the Web (well at least Chrome) and shows promise for Widows, MacOS and Linux. I believe this is great news for small to mid sized development organizations.