I've been to these, twice. The first time I was a newish PPL, and I learned a lot. The second time I'd got more hours and experience under my belt, and I'm not sure I learned very much, if anything. But it certainly didn't do any harm, and if I learn one new thing, on a winter evening when I've not much to do anyway, it's probably worth it. I haven't been for a couple of years now so I'm planning to go again.
So, not fantastic, could be better, but possibly quite useful, especially if you're fairly new to flying - that's my verdict.