Mood lighting is present in the Y+ cabins on the 777 and Upper Deck 744.
Benefits of Premium Economy aside from the seat...
* Access to premium checkin facilities
* Priority Boarding
* Business Class food and beverages (including dessert, cheeseboard, port, dessert wine, etc)
* Access to Business Class bathrooms and inflight snacks/refreshments
* Served by Premium cabin crew
* Exclusive cabins (on 777 and lower deck 744)
* Priority disembarking
Personally I like the main deck 744 product. Despite the absence of mood lighting (which is a bit of a bling bling gimmick anyway, to tell the truth), it has an exclusive feel (some pax have commented it's as close to a private jet as they'll ever get!) The only minor issue with 744 main deck is that it can get fairly chilly in that particular area of the aircraft, due to cabin temperature/zone fluctuations that are simply unable to be fixed. I'm not talking icebox here, however - it's fairly minor and an extra blanket or jumper will easily solve that problem.