Premium economy is not luxury service but it's not necessarily a ripoff either. If you can't sleep on a plane or are a larger person, it could certainly be worth the price difference for you. You get more room, usually in terms of seat width and length, and a larger recline (you can lay a few inches flatter than in economy), so you will definitely (definitely) be more comfortable. If however you are shorter than 5'9" or so, and can sit comfortably in cramped quarters for 8 hours without getting antsy, it may be a waste of money. For a small woman, it's probably a waste. For a larger person it can be a good investment. I would not fly premium economy for the perks, because as I say it's not luxury service. But I've sat in premium economy seat and they are much much more comfortable than economy. Doesn't matter very much for a domestic flight but for the transoceanic voyages, if you can't afford a layflat pod in business class, premium economy can be worth it for the larger seat and steeper recline.
Like rogerdodger said, check seat guru before booking to see what you are getting, ie. not in front of an exit row where recline is limited.
I fly business regularly but not always, and frankly it's just the lay flat that I care about. That's the only fare class difference that matters to me. I don't care about or need better food or more booze or the vanity kit or the bigger TV or priority boarding etc. It's just laying out flat, which makes long hauls so much more bearable. It would be awesome if airlines could come up with an economically viable and safe configuration that allowed economy class to have lay flats. Skimp on the amenities like entertainment and meals even, and double or triple stack me if you must. It needn't be a pod, just a bunk. If I could lay out flat on a low end cot or stacked navy bunk in economy, I'd be thrilled.