Fairly situational for heroes that don't have extra forms to switch to, and for the heroes that DO have extra forms, it's usually low-impact (as those usually aren't the heroes that get lots of extra readies to take advantage of a stat boost). I prefer my situational cards to be high-impact, so I'm rewarded on the occasions when the card isn't being discarded as a resource.
May have some value in a R&D Facility / Go All Out style deck, as it provides resources for R&D's requirement while also giving a hefty (if temporary) stat boost to power up Go All Out. OK for heroes that ready frequently (Quicksilver, Ghost-Spider) if you're playing them in Leadership, just maybe don't play a full three copies so they don't clunk up your hand at a bad time.