I've seen a lot of Emirates recently, having flown from Australia to London and back the week before last: so here goes! Decided to try Emirates this time as they had better departure times and routing (ie direct to Glasgow from Dubai) than the other carriers.
Sydney-Dubai: A340-500 in First: Very comfortable suite, as good as F in QF or BA. Liked the extra privacy that the sliding doors give you. Best entertainment system I've ever seen, lots of movies and music on demand, even some quite obscure classical programmes. Good service. Power point for laptop.
Dubai-Glasgow: Boeing B777-300 in Business: There is no First on this route, but it meant not having to change at Heathrow. Can't remember much about it but nothing bad.
Gatwick-Dubai, Airbus A300-200 in First: Seats in 2-2-2 configuration, so had to climb over neighbour to get to aisle. No laptop power.
Dubai-Singapore-Brisbane, Boeing 777-300 in First: Seat configuation as above. No laptop power.
Definitely not as comfortable as the A345. The seats were comparable to business class on other carriers and didn't lie flat. Service was variable: OK from Gatwick, excellent Dubai to Singapore, then there was a change of crew and it became very patchy (breakfast not cleared away for ages, forgot to hand out menus, had to ask them to take my jacket - it looked like they were short a couple of stewards). Little things, I know but my company was paying the premium for First!
The lounges in Sydney and Gatwick were excellent, plenty of nibbles and booze and not at all crowded. The First lounge in Dubai was something else; I couldn't even find a place to sit down. They are building furiously at the airport and this will probably be fixed in due course.
In summary - worth paying for First if you are on the A340-500, otherwise stick with QF or BA.