A couple summer's ago, I tried a less intensive plan. I memorized Invictus, which is pretty easy and I'd highly recommend. I can get through Death Be Not Proud by John Donne with a cue or two. But I realized that for me, at least, it was basically just a parlor trick, and that I got more from poetry just reading it, so I stopped about half way through If.
I definitely see how it could be come become a parlor trick. If you're doing it because you want to impress others, or because you want to be able to say "I've memorized umpty nine million poems!" then it's pretty meaningless. However, I think that if you're doing it because you want to improve your thinking, or because you want to genuinely share poetry with others, then it can be more than just a parlor trick.