It has an intuitive visual query builder and it can represent SQL queries visually making theem easy to understand and modify.

It is free if you don't need export and printing, and it has good visual SQL query builder which can show the diagram of existing queries.

There's only a little problem with FlySpeed. It does not have a SQL Editor where you can type something like this simple query:

-- example query --
SET @a := 1;
SELECT @a;
-- ends example query --

I like this app because it has a query builder more stable than MySql-Front (another great alternative I will add later).
So I'll use MySql-Front again in the future for its SQL Editor in which you can write vars and see directly your query results.

When FlySpeed will provide this feature, my thumbs will up.

[Edited by nineoclick, November 19]