To evaluate Iron Man, I usually compare him with Ronin, because they're both allies you want to slap upgrades on, and with Beast because of the similar stat line. Therefore, if you attach Inspired to each, you get:

Iron Man 6 ER (equivalent resources), THW 3, ATK 3, HP 3

Ronin 6 ER (equivalent resources), THW 3, ATK 4, HP 3

Beast 5 ER (base cost of 5, plus 2 for Inspired, minus a 2-point resource card you get in your hand), THW 3, ATK 3, HP 3

So, with only 1 upgrade card, Iron Man falls behind both Ronin (who has 1 more ATK) and Beast (who costs 1 less ER). If you also attach Reinforced Suit to each, you get:

Iron Man 7 ER, THW 3, ATK 3, HP 5

Ronin 8 ER, THW 3, ATK 4, HP 5

Beast 7 ER, THW 3, ATK 3, HP 5

In this case, Iron Man becomes equivalent to Beast, while compared to Ronin, you're trading 1 more ER for 1 more ATK (personally, I'd still choose both Beast and Ronin over him).

Conclusion: Iron Man becomes truly competitive only in a full Voltron scenario with 3+ upgrades, which however is far from easy to achieve. While not terribly subpar, he's now an outdated card and definitely could've been given more love (1 more HP would probably do the job, maybe also adding a thematic Aerial trait).

NOTE: This card has been buffed in Rules Reference 1.7 and now reads:

Alter-Ego Action: Search your deck and discard pile for an ally and an upgrade that can be attached to an ally. Add them to your hand. (Shuffle.)

"Can be attached to that ally" has been changed to "can be attached to an ally".

This means you can now find any ally plus any upgrade that can be attached to any ally in the game. For instance, you can fetch a non-identity specific ally and Sidekick.

NOTE:

On the Angel decklist card, this card is erroneously listed instead as Triage, a completely different card from AoA)

I find this card very strong. 2 ER for 1 thwart or attack and then a chump block. This is an auto include for most Avenger Leadership decks to me. Very strong with Captain America, Strength In Numbers, Band Together, and Earth's Mightiest Heroes. Stinger can also be played for free with Team-Building Exercise or Avengers Tower. Not counting against the ally limit means Cassie can be played at any time without risk too.

Rating: high A (S-D)

In my opinion, the best aspect card in the game. I don't like to call cards staples, but this fits in nearly any deck. And even if you have a perfectly fine 40 card deck and you play a scenario with a few 2 ATK non-guard Minions with a nasty when defeated effect or something like that coughthanos, tower defense,cough, you can just throw this card in and it will help a lot. Even if it just saves you a basic attack for 2, it's still practically 2 damage for 1 ER, and perfectly on curve. I also love it for Tigra to just collect the minions and keep them shut down. Hunted even ignores guard, so the weak, guard minions that are nearly in every scenario can be targeted. But it's situational and not an energy resource for the protection cards that want one. It can happen, that there is no target or just a 4 ATK minion, that you would still need to kill.