All I noticed is a new carpet and a few seats now have all purple covers without the vertical white lines. Not much of a refurbishment to be honest, a few still have Central Trains stickers inside! Honestly, Northern should give their 158's a major overhaul with a brighter interior, better lighting and an overall clean, fresh look, not a half ar*ed attempt with just new seat covers and grey carpets. South West Trains 158/159's and other 158's with ATW, FGW and EMT are good examples of what can be done to an Express Sprinter and Northern should do the same.
On the Yorkshire Coast Line (Hull - Bridlington - Scarborough) I've heard people complain about how grubby the 158's are. When I lived in Kent Southeastern did a fantastic job of keeping the now 20yr old Networker fleet in top condition and it is a shame it's not the same story here.