The acting in S1 of DS9 is stiff but it is miles better than S1 of TNG. It was Trek done a little differently so it would take time for the PtB to get how to run a space station show as opposed to a starship show.
Sisko does have some issues with his temper, despite being an "evolved human being", but he isn't meant to be Picard, he has a fair bit of emotional baggage to deal with. I will forever love him as the man who punched Q--something I wished they'd done in Encounter at Farpoint, put him in his proper place.
Kira I never saw as being a "tortured and beaten soul", but someone who was resentful of the Cardassians and then the Federation. She's not Starfleet so her first priority is Bajor, making it strong again after 50 years of the planet and people being brutalised, whilst living with all she did as a terrorist since she was in her early teens.
Bashir I wasn't a fan of in the beginning, because he came across as a know it all. But there are loads of characters on TV who pine after an unattainable woman, so its hardly anything new. He does get far better as the series goes on.
Dax is an interesting one. They obviously wanted her to be the wise, old sage trapped in a young, attractive body, but then they decided to make her more of an adventurer, to really embrace all that she has from being Joined. It can be explained away by having it she wasn't Joined for long before the series started and so was still getting used to the process (that's what I do anyway
My advice: stick with it. No series gets everything right in S1 and some still have a few issues into S2 as well, but DS9 just gets better and better, building up great story arcs, a wonderful cast of recurring characters, and very well developed main characters.