We stayed there from July 30th to August 4th 2006.
Probably one of the worst period of the year as it was pretty warm (around 40C) but also very humid.
Still, we just planned to stay there to enjoy the pool, restaurants, spa and shopping centers, so the heat was not a real issue.
The hotel is very different from the rest of the hotels you can have in Dubai. Most of them are "vertical". The Royal Mirage complex must be the, or one of the biggest Hotel resort in dubai. Blocks are 4 or 5 levels max shaped in some kind of arabic style. Very nice, luxurious.
We had a gold club room, which I guess makes to real difference from the standard room. The main difference for us was that it was very close to the swimming pool, and we had complimentary snacks and drinks at the Gold club lounge throughout the day until 7pm.
The pools are great, the temerature is kept around 28. (The sea temperature was around 37C in the morning, yes, 37!)
All the restaurant we went to were very good (Olive, Tajine) or excellent (Nina).
The staff is very friendly and efficient. The hotel is in perfect condition, always very clean. The rooms are done at least twice a day.
We loved it.
If we go back to dubai, we'll probably return there.