That's only true if the card is still a planeswalker, not for planeswalkers that lose the planeswalker type for the turn, like Sarkhan, the Dragonspeaker
This and another choose two modal spell, Atarkas Command, are great at dealing with a variety of situations
The mana value is pretty stiff at six total mana, but it can be effectively an extra three cards to hand per turn, spot removal, or a good boost to every creature on our board
While you wont find anything in the league of Umbreon ex from Prismatic Evolutions here, more than a handful of cards are worth a decent value
As of the time of this writing, weve seen four other cards with shield counters: Disciplined Duelist
Can you survive an extra turn to play Blood Sun