The thing is that LINQ's purpose is not to reinvent SQL. While EF has an adapter which converts LINQ expressions to SQL, you can use LINQ against objects and other sources for which it is incredibly useful. In fact, it's better suited to those tasks as it doesn't map 1:1 with SQL. But as someone who uses EF and LINQ on a daily basis, it is possible to learn how the mapping is performed and get the results you want consistently even in some pretty advanced scenarios.
Side note, I fell in love with the Mongo LINQ driver. There is no impedance mismatch. While I never used LINQ to avoid learning sql, I would create my complex Mongo queries in LINQ first.
