Actually Black Lotus isn't really all that good in a format where you only run one in your 100 card deck. Sure, it's awesome if you get it in your starting/first few draws but if you get it mid-late game you're probably not hurting for mana.

Now a standard game of magic where you're playing a 60 card deck and can run 4 copies... Your odds of drawing and taking advantage of it early are pretty damn good so it's quite powerful.

But unless you can use it as a combo piece or something it's cool rather than good in commander (not that it's bad, it just isn't crazy).