Very pleasant sounding song. I can't really sense nerves in the performance, so you did a great job making him feel comfortable and getting him to deliver.
I wrote down my thoughts before looking over the thread. I then went back and checked out a few other opinions. I am seeing a lot of well deserved comments that the mix sounds good, but without much critical feedback. I am not overly familiar with your work or your production style, so I don't know why this is. I can make an assumption that it is very likely framed within a sense of familiarity that a lot of long time posters have with your work.
The mix is indeed nice and has a definite character to it, but it also has some areas where it could improve. Perhaps this is subjective and again, perhaps this is mostly due to your personal style and choices that you make, but I will throw it out anyway to see what you think. Like with everything else, it's opinions and of course, keep or sweep as they say, but I'd love to hear back on the points I am making.
There is a cloudy or hollow sense to the mix overall. I am getting a lot of buildup in the lower mids. It sounds to be in the traditionally problematic areas between 350Hz and 500Hz. I think some cleanup in that area will do wonders for opening this up.
The whole affair is coming across very mono despite the fact that I do hear elements coming to me from the sides here and there. Perhaps this is designed as such for target playback systems, but on a nice stereo system, it is making it feel confined and congested.
Different song sections aren't quite opening up to their potential. There is not enough contrast in levels or instrument focal points as we move from one area to another. I am getting a strong sense that each individual element is either limited, clipped or generously compressed to be very steady as an individual element, and the result is that as we move from section to section in the song, it all stays very steady in terms of overall dynamics. The dynamics and the interaction between different instruments and the vocals within a particular section are good, if not a little bit overly controlled, but section to section needs work. A nice piece like this should bloom and open, then contract, then repeat.
Overall, a pleasant listen and I certainly hear potential in the song and the production, or I wouldn't have taken the time to put these thoughts down. Hopefully this helps a little, even if just to spur some conversation. I really like to listen carefully to the works of others because I find that I learn a lot this way, so getting to the heart of choices that you have made with this mix would be very interesting.