I played it as a one of in Maverick and it was fine. I think decks like GB Rock and Dead guy love these though. Not that those decks are remotely viable because they aren't blue
Well, where it actually does fix mana, by offering access to both colors, the needle definitely moves. In a mono-color deck, to me, they are worse than basics in most cases.
"The Ancients teach us that if we can but last, we shall prevail."
—Kaysa, Elder Druid of the Juniper Order