Like modern soccer, you need a lot of money to thrive and achieve success. Top Eleven 2015 is a nice game, with a good management system and a whiff of the old Championship Managers, but is ruined by a pay-to-win approach that basically forces the player to invest money in order to advance in the game.
Top Eleven 2015 is the kind of experience that should have probably stayed on Facebook, where its limited mechanics and its money-driven elements feel more at home.
If this sounds like your type of football management game then dive right in. However, for an iOS football manager there are other solutions out there, especially if you are willing to pay for them. The far more in-depth Football Manager Handheld 2015 from Sports Interactive for example.