Internet app needs to be really secure. So LDAP for auth got into the game. Instead doing the traditional db with users table, we want to authenticate agains a LDAP server. How good/bad you think it is ?
In principle, there is no fundamental difference in security between a "normal" DB and LDAP if implemented with equal care. However, there will be no benefit when compared to a DB if you use it to authenticate just a single app. The main advantage of LDAP as a user database is that you can use the same users in many different contexts and it can easily fit into a hierarchical model in an enterprise, which is difficult to achieve with a classic database.
What benefit would you expect from LDAP?