It's true that many PR teams in councils are hopelessly under-resourced. I still come across district councils in particular who have no-one working on PR or rely on the efforts of someone who has a full time job doing something else in the council. But there are an increasing number of councils at the other end of the scale who now have big PR budgets and run campaigns that would be the envy of their private sector counterparts.
I think the key difference to working in the public sector is politics, and this is something that private sector colleagues often don't understand. I've seen many highly experienced private sector communications directors fall foul of national or local politics when they make the switch to the public sector.
I recently advised someone who was facing a major public sector re-organisation of their service due to be announced at a private meeting with ministers and couldn't believe the vicious pre-briefing that went on in the preceding weekend's media. You could say this was naïve but the impact of politics on your ability to do the job has to be seen to be believed. There is an edge to working in such an intensely political environment. It is stressful it's true, but it's also some of the best training you can get to hone your PR skills.