Uhhh, the new gideon is quite good. He's literally a one-sided The Abyss in creature matchups and he still provides a solid threat against control because he can only be taken care of by selesnya charm (in creature form, obviously o-ring and the like still work). He also only costs 4 and is better than Gideon Jura most of the time, which is pretty insane. You also literally cannot lose (a real game, obviously if they have mountain + lightning bolt and you are at 3 you *can* lose but you would have lost 10 turns ago if they had that) if you use his ultimate, which is generally a good sign for a planeswalker (I've lost games where I used jtms ultimate fwiw, because the board position remains unchanged).
No. Aboslutely wrong on virtually every single point.
First, the ultimate might as well say "-1000000:" because it's exactly as achievable as -15.
Second, even if you actually did get him up to 15 or more counters, his ultimate is actually AWFUL because it
removes your board too. All you're doing is turning it into a topdeck fight with your opponent. It's like Karn's ultimate except it costs more Loyalty, and you don't get any cards to start with, and you don't get a new hand, and you don't get a reset life total.
If you ever get 15 loyalty on Gideon, you're practically always better off just attacking with your indestructible 15/15 every turn - you'll win faster.
In fact, just to get 15 loyalty in the first place means you've been gaining loyalty when you should have been attacking with an 8/8 or 10/10 already.
He can't protect himself. He can't protect other Planeswalkers. He doesn't generate card advantage. He doesn't even protect you. All features that the Gideon 1 had. Gideon 1 DESTROYED Aggro matchups - Gideon 2 either gets ignored and you die, or the creatures just attack him, he fogs a turn of damage and you're left with a 2/2.
Basically, Gideon 2 is not even a Planeswalker. He's a 4-mana 6/6 growable creature that is resistant to most removal but with no evasion and who doesn't synergise well with Auras or Equipment or Soulbond. The decks that want an effect like that (basically white weenie only) aren't even good in the first place, and they have plenty of other options, arguably better (e.g. Sublime Archangel, off the top of my head).