Someone summed it up on here beautifully a few weeks back - whenever I see Shirley, I see two completely different characters that do not mesh with each other, depending on the writer.
One character is the tough old woman who's had it rough and, at first, seems pretty nasty, but ultimately has a big heart who cares for her friends, and will do anything for them. She'll stand up to just about anyone who threatens her or people she cares about, and will take crap from no one. She's done things in her life that she wasn't proud of, but ultimately is trying to make up for those.
And then there's the other character - a bitter old woman who's spiteful nature has driven everyone she cares about away. She's selfish, horrible and will spit on anyone to get what she wants, even people she pretends to care about. And every time she messes up, she hides behind her "bad past" as an excuse for it, and goes on to mess up all over again. She never learns, never develops, and is just a nasty piece of work.
... And these two characters just never mesh, despite how much DTC wants them to. It's like the Lauren Problem that Newman had a few years back - shoving your pet project character into the limelight, begging us to like them, will not make us like them if there is nothing to like. Shirley has more storylines than anyone else, pretty much, and in them she's either one character or the other.
I'm in the dislike camp. I get what DTC is trying to do with Shirley, but his insistence on keeping that low life Dean around, just so we could have yet another baby plot featuring his other pet characters Kush and Stacey, has really not helped. Linda Henry is a fine actress, and Shirley in the right hands could be a very special and engaging character. But she's overexposed, overused and ultimately, let down by weak writing.
It's funny with DTC. His biggest weakness as a producer is not identifying when something just isn't working, and dragging it on regardless. Oh, and the fact that he thinks having 10 baby plots at once is engaging television, and not the lazy, boring writing it is. Look at this week - no babies, no Shirley... and all the better for it.