With the new version of VS 2013 RTM and asp.net mvc 5.0, I’ve decided to try out a few things...
Needless to say, a lot has changed. For example, the new ASP.NET I
you can create your own UserManager completely,wich i don't recommand unless you have a strong knowledge about how it works.you can wrap the existing UserManager and make you application rely on an interface or just use it directely and benefit from what microsoft has put in it.if you don't like EF you can create your own Store to use another Database. the new ASP.NET Identity is extensible enough,i agree that is kinda Hard if you want to take full controle and customize everything,but i recommand taking time to understand the most of it so you can choose when to use or not.most of time it's enough to use the existing UserManager.