The tittle says all, but if you think about it, shapeshifting as it is commonly represented is lame as hell, example, mystique (though this is movie mystique, i ain't got a clue about comics) oh you can turn into other people? Cool, question though, fuck's that gonna do when someone like wolverine is trying to tear you apart?
And don't think the other common representation is any better (turning into animals) it is, granted, a bit more useful but still, fuck's that gonna do when someone with super strength (not even all that high tier too) decides to make you their punching bag? A speedster is gonna kill you before you can even change, and more complex superpowers just leave you in the dust.
It's only real application is infiltration, and if that fails because X Y or Z? Well, you're fucked.
And it sucks because shapeshifting can be disgustingly powerful, you got wounded? Nope, just shift back, need a weapon? Claws, fangs, quills, take your pick, need transportation? Wings, ultra dense muscle, whatever you want, need defense? Chitin, scales, redundant organs, the sky's the limit, and the best part? All that, at any moment, in any form, however you want.
TLDR: shapeshifting has a lot of potential, but it's more famous varieties suck
Edit: i definetely worded my complaints wrong, what i'm complaining isn't if the powe is or isn't useful, or if the characters mentioned have or not better feats, what i despise of the more popular representations of the power is how restricted and limited they seem, being able to ONLY turn into another person, or an animal, feels really bland to me, more so compared to other representations (not even extreme ones like alex mercer from protype) where the power feels like a tool to be as creative as you want to be, go body horror, or not, be a chimera, or look human with inhuman abilities, this is to me what shapeshifting should be more commonly know as, creativity to alter and change