This is more a matter of taste than anything else. Compared to the Java I would say it's much cleaner (Personally I don't care for Java). Compared to Kotlin, it is more different. Flutter uses a declarative programming model so it is conceptually very different in terms of how you think about an application. There are a lot of nice things about this model for basic applications, but things get complicated for certain applications (AR/3d for instance). Also it is also open sourced (BSD) so the fear of Google dropping it is not as grave as the company's proprietary 1p product offerings.