Got Pfizered about 90 minutes ago, can't really lift my arm, my back aches and I feel a little out of it and I couldn't be happier.
I got the 'derna, and had the same thing with the arm. It felt super heavy for half a day. Then a little malaise and all good.
It wasn't heavy as such (apart from maybe the first six hours when I was still a bit dazed) just any movement 'the wrong way' felt like tearing every muscle in it, nearly back to normal this morning though... unless I poke it.
A day and a half with only one arm working and sleeping on my right side was worth a little avoiding a potentially horrible death.
I did get some further effects (although as forum age goes, I'm on the lower end which seems to impact reaction severity) the Saturday gave me a very bad 2 hour dizzy spell and some minor heart fluttering through Monday and then a 103/72 blood pressure drop on the one week anniversary, which took it out of me for a couple of days, but totally back to normal now and I've just done several days strenuous work.
A friend of my mum's, son, apparently had heart fluttering too and was understandably quite panicked so a potential side effect to be aware of, although I feel I should say, be sure to follow up with your medical practitioner.