I don't think I would call them easy, you have to stand and stir a lot, and the syrupy sauce is kind of like lava, you definitely do not want it splashing or dripping on you skin.
Ingredients are pretty basic though, but you really need to use real lemons not the bottled stuff because you also need some grated lemon rind.
I would imagine Key lime pie filling stuff is pretty similar, but I have never made that before.
I will make and have some more one day, but right now I am doing really good on my blood sugar numbers so I do not want to screw them up.