I have no experience with Royal Canin. The only food I ever felt great about is Nature's Logic. I fed it to mine for a couple of years and only stopped using it when the shipping cost just got to be too much for me. If I could get it locally, I would still be using it.
It is on the high end as far as protein goes (38%) and some feel uncomfortable with that. I had no problem with it, but all mine are healthy, active dogs. Others may not have the same result, so I wouldn't 'recommend' it. I would say it's worth checking out if you're looking to make a switch, but some basic nutrition research should be done when making choices.
I mentioned earlier about The Dog Food Project as a good source of info. There's really a lot more info there than just comparing brands.
The Dog Food Project - How does your Dog Food Brand compare?
Here's the Nature's Logic site if you're interested.
Nature's Logic
*This is my opinion only and is in no way geared towards those whose dogs may have special dietary needs.*