Generally, a hero with a stat line of 2 ATK, 2 THW, 3 HP costs 3 and has a positive ability. In order to be as good as that, Tony here needs to be discounting at least two upgrades, so you'll want both several types of upgrades (since they're all limit 1 per ally) and multiple copies of each (so you can assemble them in a timely fashion). And then you want Call for Aid and/or other allies who are exceptionally good to play upgrades on (e.g. Ronin). And probably something that can restore HP on your huge investments. So this is not a card to throw in any old deck, but it can be good in the specific archetype.
In addition to all the Avenger upgrades, if you go with Star-Lord and/or Honorary Guardian, you get access to all the Guardian upgrades and Guardians of the Galaxy as well. Play an upgrade for 0, immediately draw a replacement card? VALUE!