My actual thoughts on the card (rather than my campaign to fight against bad comparisons in card evaluation) are:
Let's start with general concepts when it comes to evaluating planeswalkers. First, individual planeswalkers have significant diminishing returns with additional copies. The first JTMS might be the best possible walker you could possibly be playing at that moment. However, the second JTMS is either FoW fodder or a card to be brainstormed away. Not necessarily a dead card but certainly not as good as an additional walker you could cast and have an impact on the board, such as a Dack, Teferi, or even Arlinn. This is the first half of the ... "Superfriends theory" (I'm making up names for these concepts as we go...).
The second half is that, by the nature of having several abilities, planewalkers are often capable of serving multiple strategic roles. They are not equally adept at performing these roles. To continue with JTMS, I think it is generally accepted that his Brainstorm ability is his most powerful mode. This gives Jace the primary role of a card advantage engine. His other roles are as a win condition (through Fateseal into the ultimate) and removal (the unsummon). However, if forced into these roles, Jace is suboptimal. The Modern format exemplifies how the roles Jace, or any walker, fill may be inadequate given a format's constraints. Consider Teferi, Hero of Dominaria now. Teferi also has a primary role as a card advantage engine, but is weaker than Jace as drawing a card is less powerful than Brainstorming. At the same time, Teferi is a more resilient card advantage engine given his starting loyality and uptick to draw. Teferi is also the better removal spell, as his -3 can target noncreatures, effectively puts the opponent down a card, and does not allow the opponent to recast the target the next turn. Now it might be tempting to debate which is better for Vintage by focusing on these roles, but it's not of incredible importance when it comes to deck building. Just like the diminishing returns of individual planeswalkers incentivizes more planeswalker diversity, the variable roles of planeswalkers also encourages more diversity. It means I can use JTMS as a pure card drawer, knowing that Teferi is in my deck to answer the random Oath of Druids or Planeswalker the opponent might be able to cast. Or that I will draw a Chandra or Nahiri or Arlin to actually close out the game. A name for this: "role optimization".
Because of the Superfriends theory, I tend to spend much more time looking at the strategic implications of new planeswalkers and looking for synergy than I do comparing them to existing planeswalkers. So let's do that now. I think it's pretty clear that Tezz 3.0's best ability is his 0. His +1 ability combined with his starting loyalty makes him very difficult to kill the turn it comes into play in modern formats. If upticked, you are looking at 6 loyalty and a 1/1 flying blocker. It makes it likely that its controller can untap and start to take over the game. Now, this point is somewhat moot in Vintage and Legacy, where I think the majority of planeswalkers that are removed are either countered or Pyroblasted, but I try not to have tunnel vision for just Vintage, as you never know when interactions and tech from one format might find their way into Vintage. Most recent example is "Teferi + Search for Azcanta". In any case, I would classify Tezz as a strong and resilient pure card advantage engine. I think his capacity as a win condition is negligible and he really shouldn't be used for this purpose.
Now what cards work really well with Tezz? Again, I tend to consider other formats when evaluating cards and I think Tezz is going to be a format defining staple in Standard. This is mostly due to the rather absurd synergy between Tezz and Karn, Scion of Urza. Karn's ideal role is pooping out constructs, making him a midrange threat or control finisher. It just so happens this mode generates Artifacts for Tezz's 0 and protects Tezz from being attacked, allowing Tezz to function as a pure card advantage engine without having to use his +1. Speaking of the +1, if drawing cards is not necessary at a certain stage of the game, assembling Thopters is much more impressive when those Thopters are pumping up Constructs. I'm actually considering buying into Standard on MTGO to explore this interaction, as it seems very powerful in the context of that format. In Vintage, it might not be powerful enough, but it's something to keep in mind in trying to find shells for Tezz.
The other card that works really well with Tezz (and is actually Vintage-related) is Dack Fayden. I don't think this has been discussed in this thread, but it's something that immediately jumped out at me when I looked at Tezz. Dack's -2 ability has the effect of both increasing the amount of artifacts on your side of the board, along with ramping from 3 to 5 mana to cast Tezz the next turn. Dack's +1 also is more powerful with raw card advantage and Tezz generates that more quickly than other planeswalkers. Taken with 4, I can see a powerful Vintage shell forming around Dack, Karn, and Tezz, and that is indeed my starting point for playing this Tezz in Vintage.
Note, I didn't really answer whether I think this card is playable. I just tried to arrive at the ideal starting point for a deck that would use this card. If I think a card is unplayable, it will generally be because I can't find a shell that really utilizes it after looking at its strategic roles and synergies. The ultimate determination of what makes a card playable in my opinion, I save for testing (which I plan to do on stream).
If you found this approach interesting, please let me know and I will try to talk through my evaluations of other cards.
Great post. That really sets the bar for how card evaluations should be done. This new Tezzeret also has great synergy with Tezzeret 2.0.