I think we need to make the distinction of "Before Rick Came" and "After Rick came".

BRC: As far as Deanna knew, people weren't much of a threat.. she probably figured most were like themselves, just regular people thrown into a scary situation.. and most would be like Enid.. alone, or in small groups, and looking for a safe place to stay. There are always the types that don't fit into society, but banishing them takes care of that. Providing food, education, entertainment.. these were things to keep people healthy and occupied, and gave hope for continuing to make things better and better.

ARC: Deanna had, for 2 years, been telling herself the above. Rick and his group came, and began chipping away at the happy little world she had built up in her head. She was strongly in denial, and refused to take his advice.. until it was too late.

I don't think most people would think she was a bad leader at first. It was her staunch refusal to entertain Rick's notions that made her a bad leader.

She's coming around now, a little late perhaps, but there is still a town standing, and better late than never. Even though she thinks the townsfolk would do better with Rick as leader, and has said as much, the townsfolk aren't ready to listen to Rick. Deanna will keep some amount of power for a while longer...

 

Given the circumstances, I don't think Deanna has been a bad leader. Their knowledge of the apocalypse has been pretty limited though. They haven't encountered any real human threats yet, and most of the walkers that would have made it to Alexandria have been trapped in the quarry. That's made things relatively easy for them. She had to exile a few people previously, so she obviously realized that people could be a problem. But there's a large distinction between this and the types of problems with people that are actually happening in the world. Deanna had to exile them because they "weren't working out." Meanwhile, Rick and Co. have had people attempt to rob them, roll up to their gates with a tank and dozens of guns, try to EAT them, and numerous other problems. This is pretty distinct.

Had the circumstances in Alexandria been different this whole time, I'm sure a lot of the things that Deanna does would be done differently. Up until now she hasn't really seen a reason to post a watch on the walls. The walkers are just going to walk into the side of the wall...and she didn't really see people as a threat. She figured that any people who came by would just knock on the gate and ask if they could join their community. She didn't think they'd get firebombed, have people climb over the wall, and then slaughter a bunch of their people.

Deanna hasn't been a bad leader, but she isn't the leader that they need. She has organizational skills and planning skills that are crucial to making a community survive, but she doesn't have what it takes to survive when there's an actual enemy out there.

 

Is not that Deanna isn't a leader she just has a different skill set. One of community planning and managing people who do societal tasks. She started recognizing that the world had changed and she needed someone from the outside. Thank goodness she found Rick. I love the way she interviewed everyone that came in. She is a great leader she just doesn't have the skills or leadership to provide security. The relationship between her an Rick is much like one of the executive branch and the military. Who is in charge is still evolving but no matter how it goes down Deanna will still be a person of great influence.

She has a vision of maintaining a society through the biggest threat humanity has ever seen and she has not given up as shown in the scene where she was still drawing up plans.

One also has to take into account she is still only days removed from the death of her love. She is a strong character and a good leader who got those people further through the ZA than most.

Rick and her actually have a lot in common, Rick's vision of the prison was much the same as Alexandria. And also when pushed against a wall Deanna makes the tough decisions.

 

Deanna has been a good politician. She keeps people happy even if it means using propaganda (ex. nope no zombies here.) Whether that makes her a good or a bad leader I think is debatable but in the context of a zombie apocalypse its ultimately just a matter of time before a leader like that gets everyone killed.

 

There's a mega thread on this that I started in the episode 4 forum that covers everything about Deanna - good and bad.