Effective Lean Agile involves iterating short cycles of development, each contributing more clarity to the final solution, with the customer very active in ensuring correctness of the solution. This 'iterative' method of developing in short cycles with the customer with a key position at the helm until product delivery (and even after delivery) is call Lean Agile. Does it work? YES, but you need to understand Lean and practice it almost religiously.
Lean Agile is a ‘Customer-Centric Approach’ to Software Development which requires customer participation until the product is complete and even after. So, who is this 'customer' ?