I just bought my 3rd set of m520s today (3 different bikes.) I got them when I first started riding clipless because a lot of reviews said they were easy to use for first timers, and I would agree with that.

I considered looking at other pedals this time around, but in the end it's hard to beat the 520s for the price. They are cheap, so if you end up wanting to change them after a while you won't be out too much. They are double sided, but I'm pretty sure you can buy a platform that clips in to them so you can ride one side with regular shoes if you want to go somewhere without your bike shoes.