Never bought a first class ticket, but have been upgraded a few times as a compensation. (once for a delay due to the fog in DXB... the second time due to a check in agent mistake...)
Yes , it is a great experiience. I remember the taste of some wines, my personal DVD player, with a great choice of movies.
And the bed !!! First time I can really sleep on board a flight !! When you arrive, you feel the difference.
If one day I have enough money, it will be my choice for long flight (over 09 hours). And only if it is a real business class, not a "business/first". I remember my september flight CDG-STL with TWA. It was a business class seat, below the average (compared to AF, BA, SR, LH,...) But the price was really close to first class !!!!!
Luckily for me , this time, my company paid the ticket !!!
Ecoute les orgues, Elles jouent pour toi...C'est le requiem pour un con