I have tried it and was not impressed enough to stick with it. If you are an expert and it suits your workflow then OK, but for most people it is better to stick with a common format, Photoshop. Like it, or not, it always has a way to acheive the result that you want and almost every tutorial includes a photoshop version.
As I noted above, if you are already an expert and have nothing more to learn then you won’t need tutorials, but for the rest of us, myself included, they are the easiest way to improve your post-processing. As to which program has the best RAW conversion, well maybe I’am a little stupid but to be truthful I can’t see any difference at all, they all look equally good.
I use Nikon Capture 4.4 for half of my shots, Bibble Pro for the nature shots and PhotoShop accidentally. After upgrading my laptop for a desktop with 4g ram I will use Bibble. That’s very effective and it’s easy to organize the photos inside the program. I didn’t like Capture NX, I think it’s too slow and awkward to get around in it.