is it a good project structure in DB-First approach? [closed]

This days i'm thinking about this question that does it a correct approach to build a C# project?!

Actually we use this structure to build a DB-First project:

1. Domain layer: this is a POCO class of our entities in Database
2. DAL layer: this layer works on CRUD methods on database (ADO.NET Entity Data Model)
3. BLL layer: its a business role layer, for example Access to a method or ...
4. UI layer: its a MVC, WebFrom or ...
5. Test layer: it usually is a WPF project to test methods

This structure works very well and we don't have any problems so for because someone just taught to me and i used it without any question.

Now the question is i don't know what is advantage or disadvantage of this approach?! And how can i improve or change it to a better one?