It can be OK as a cheap mini wrath for a control player who can get some use out of the other ability with tokens etc but at that it is not worth a cube slot, certainly not a gold one
As an added perk, any time one or more +1/+1 counters are added to Pensive Professor, you draw a card
Special Guests Special Guests cards bring pieces of the Multiverse together, with artwork and flavor themed around their set
True value comes from a combination of rarity, demand, condition, and cultural significance
Pili-Pala and Grand Architect combine on their own or from the graveyard with Necrotic Ooze to go infinite if you're into that sort of thing
That being said, being able to destroy any artifact for a lowly one mana is pretty good