BA thinks it is dire. If you are flying in F and you comment upon the lounge, BA will immediately buy you admission to another (better) lounge at DXB or issue you a food voucher. They are obviously embarrassed about the lounge there. At least this has been my experience (and my comments were mild, merely asking if this really was the lounge that they used).
As for whether you should eat prior to boarding, absolutely if you are at all hungry or fussy about food. The DXB catering in F is atrocious, surprisingly so. Cheese is about the only highlight of the meal (and the wines are the usual ones, DXB is definitely not dry).