Personally, I have kind of an issue with Live Nation, given its rocky past with Clear Channel Communications and Ticketmaster, so I can't really recommend the app just to buy tickets with. The company's never really been generous to customers, to say the least, taking advantage of high ticket fees and the artists that it works with. If there's an alternative way to buy your tickets, either from the venue itself or from the artists involved, it'll probably be cheaper than Live Nation, and better for the industry at large.
But they are a huge company with a lot of partnerships going, and quite a few shows nowadays (if not all of the big venue shows) are sold through Live Nation. So if you're planning to buy tickets with them anyway -- and sometimes you don't have a choice -- using the app will give you some nice bonuses.