I think it would depend on the meta a little.
If you're looking for a 3 drop mana rock, there are a lot of better options. Would you ever choose this over a
Chromatic Lantern? Probably not. But if you have the decent ones covered and want more, superfriends is about the only place this could shine.
On the plus side for this, it does have the potential to generate a decent amount of mana. As Judaspriester rightly says, Planeswalkers being tapped is rarely significant.
The downsides as I see them are:
1) Superfriends tends to span at least 3 colours, usually all 5. Dedicating a slot to a rock that doesn't fix some or all colours doesn't seem good. 100 cards feels like a lot, but a deck soon fills up. Is this actually worth a slot? Especially as activating planeswalkers doesn't cost mana. Obviously more mana is good, but is a decent amount of colourless mana worth enough to give up the potential to fix?
2) It only generates a lot of mana if you have a lot of Planeswalkers (or more specifically, legendaries, but seeing as we're talking superfriends I'm making that assumption). This is why I think it is meta dependant. If they find that their walkers are sticking around then it seems good (as in, consistently having 3 or more on the battlefield). If they are consistently getting removed/destroyed, then it doesn't seem worth it.
TL;DR
There are better rocks out there at 3cmc, but if there was ever a place for
Honor-Worn Shaku to shine, it's in Superfriends, especially if they find that their PWs aren't getting removed all that much.