I don't take too much notice of passenger surveys/reviews as they're not at all representative of how many people go though the airport, or indeed are rated on what actually influences people's choice of airport... however worth noting that after almost entirely awful reviews for STN on Skytrax for a while now, I notice the most recent 3 are positive.
I can't say I'm really surprised, a noticeable improvement as of late. I think in part it's due to winding down after the busy summer period, but still much better nonetheless.
I've noticed the route through the new shopping area has now opened up (albeit most of the new shops are not open yet), giving more space. Noticeable increase in seating availability and overall a more relaxed feel. Looks much more complete and increasingly less like a building site. Passport control getting marginally better on the whole too.
I'm not saying it's perfect, but definitely an improving picture.