We got back from Mauritius last week, business there, PE back owing to no availability in business. We are usually more than happy in PE but I'm 32 weeks so comfort was a huge factor. BA flight back overnight, we had 3 babies in the front row and two very young toddlers, all of which took it in turns to scream at regular intervals, making sleep very difficult and broken (heavily suggest loop earplugs, not the crap they give you). When the seats are fully reclined in front of you, the only way out of a non aisle seat is to climb, you cannot stand up to get out to the loo. The loos were all the way back in Economy, admittedly walking through there looked like a refugee camp at 4am with people just trying to sleep however they could manage, meaning a lot of legs to climb over to finally go for a pee.
Not my overall favourite experience longhaul. BA premium economy is pretty much the worst of the premium economies, Norwegian air was brilliant, so much more space.
So, is it worth it? Well, it was bad enough in PE, I can only imagine the hell of 12 hours over night in economy, so probably. But, if you can, go business. That was epic.