I'll save your time and get straight to the point. If you want value for money, feeling welcomed by locals and hotel/service staff, and a real tropical paradise feel from your holiday, DO NOT go to New Caledonia.
Now the details:
We arrived on October 13th and stayed 1 week at Le Meridien, arguably the best and most expensive hotel in Noumea. The hotel itself, our room, huge breakfast (included in the price) and hotel staff - were all very nice, I'm trying to be fair here. This is where the good stuff about the holiday ends, sorry.
First of all, the whole week was really really bad weather. We had 1 sunny day, and while other holiday destinations offer you a number of other activities when the weather doesn't let you go to the beach or swim in the pool, there is literally NOTHING to do in Noumea. The town is dirty, has a "poor Southern France" feel about it, with no real exotic tropical island atmosphere or attractions to look at.
The water was cold, even though the travel websites told us that we should expect 26 degrees Celcius. I think it was more like 17 all the time - as it was really really cold and swimming was virtually impossible.
Locals are not particularly friendly or unfriendly, but the white French population of the island will literally hate your guts if you speak English or simply - not in French to them. I'm sure lots of people will try and "boooo!" me here, and there are exceptions, but overall they do not like non-French people here and you'll just have to deal with this fact whether you like it or not.
It will be hard to get directions, prices in small local shops will be lifted x10 times from their normal "French" prices (I personally wanted to buy a bottle of a soft drink for 130 Pacific Francs (the price tag was on the shelf), and the guy told me that the actual price is 1300 Pacific Francs. I kid you not.).
It is also worth mentioning that everything in New Caledonia is ridiculously expensive. I know that all holiday destinations and tourist places have their prices lifted up, but trust me - New Caledonia stands out. When you start paying $30 for a burger and chips, and $80 per person for a half-decent dinner, you'll know what I mean.
The only nice experience in our crazy rainy boring week in Noumea was that 1 sunny day when we went on a day trip to Amedee Island (the one with the lighthouse on it - my spelling of a French name might be off a bit), and that was a total bang for the buck - the buffet lunch, national dancing, the boat, the island itself, magnificent.
So, sorry if I rained on your parade, but I hope I just saved you 7 days of your precious time and a couple thousands of dollars that are better spent elsewhere, where you feel welcome, can get unique local experiences, cheap nice food, friendly people, and a _proper_ tropical holiday.