It's a crappy business class seat, no doubt about it. It's narrow and the recline isn't great in this lie-flat era. But those who say they would sleep just as well in economy... well, I guess each to their own, but I'd say it's a significant step up in sleep comfort from Y.

As for whether it's better than a decent premium economy seat, now that's a more realistic question. I'd say marginally yes it is, because you have a footrest and slightly better recline. If you calibrate your expectations to premium economy plus, rather than business minus, you'll probably be more or less on the money.