Having first appeared in 2012, statistics from more mathematically-inclined folk than myself state that Clara is the longest serving Doctor Who companion bar Jamie "Randy Scot Bastard" McCrimmon in terms of continued consecutive adventures. Yet, oddly, she still hasn't quite sunk into the public consciousness like the comparatively-blink-and-miss it Rose and Donna. Still, maybe next time.
In some ways I'm not sure I ever "got" Clara. Maybe it was getting three separate introductions to the character, or the fact that she was pretty badly defined in her first season (understandably overshadowed by other events in 2013). While we constantly got the impression Clara was an iceberg with hidden depths, it was hard to guess what they were with the huge misdirection that she might have been evil. Of course, this was remedied soon enough when it was decided to focus on the horrible psychological damage she endured aboard the TARDIS - unlike Amy Pond who's mental health records needed two folders, Clara's undoubtedly the companion who really needed to see a therapist. With her pathological lying, martyr complex and crippling guilt issues it'd have been interesting to see a Turn Left take on how Clara would have probably burned out without the Doctor's influence.
Of course, being the longest-running NuWho companion (she's got more screentime than half a dozen Doctors) she has suffered the usual Moffat twists of fake-departures and fake-deaths. She's been blown up, fallen down, mind-wiped, frazzled, erased, ripped apart, exterminated, duplicated just as many times as she's left the TARDIS on good terms, bad terms, popped out for a moment and vowed never to return. But ultimately she stands as the Companion Wot Died, rivalling only Adric in this regard. Yeah sure you can put up names like Oliver, Kamelion or Molly but the fact is only Clara and Adric were around long enough for it to hit home to the audience when they karked it, popularity or not. They also both fatally overestimated their abilities trying to solve the problem the exact same way as their best friend.
And yet, as fandom (currently in the "everything produced under the logo is precisely what we hate" phase that seems to alternate with Prime Ministers) seem so utterly sick of the sight of Ms Coleman and have apparently been begging for the character to go approximately five seconds before they knew it existed, I'll miss her. In her last season she's only really been in four stories, either sidelined or body-snatched or simply a ghost. Jenna's natural charisma, motor mouth and amazingly awesome Bambi eyes were at times the only comfort to be had in such miserable times as Trenzalore and 3W and various points in between.
I'll miss her, perhaps because for the first time since Charley Pollard there's been a companion around long enough for me to get attached. While I may not be a clever boy, and I'm certainly not a runner, with the aid of some band called Simple Shelter covering Enya, I've at least tried to remember the impossible girl...