I suppose anybody can tape and mud and texture drywall, it all depends on what you want the finished product to look like. If you want something to look really good, then hire someone who does drywall for a living.
When we did the daughter's three season porch which was 10ft b 17ft, the daughter and I hung the drywall and then we hired the finishing done by a professional drywall guy. He had two helpers with him and they taped, mudded, sanded and textured the walls and ceiling with "knock down" and they were done in one day. It cost $850 and was worth every penny of it, they did a super job. We could have done it ourselves, but it would not be done in a day, probably take us a week, and it would not look half as nice as what it does now. Sometimes it is best to just bite the bullet and hire something done.