This is great plugin which i personally use for my site. Quite easy to set up, yet very powerful, quite flexible.
However, the UI isn't really that intuitive, we need to scroll a lot to take a look at what this plugin has. Wishlist has easy checkbox to change the settings, while this plugin doesn't.
I would really love to has the option to make each level as a stand alone level.
Which means that level 2 isn't higher than level 1. It just different level. That way i can sell multiple products or multiple membership for different product easily.
Well, it's free... can't complain, but definitely has room for improvement.