That's a cute shot, but you appear to have hit your focus right on the bear, leaving your son a little soft. Shooting at f1.8, even from that distance, is going to leave you very little room for error so you need to ensure you hit the focus bang on his eyes.
The lighting may not have been great (shot at 1/50) but you want to try and shoot with the nifty between f2.8 - f8 where it seem to be it's sharpest, even if you have to push the ISO up to 200/400.
Not too keen on the background either. It helps to have a plain background with this sort of portrait shot as it keeps the focus on your son. At the moment my eye keeps getting drawn up along the nice diagonals
The side lighting is also a little harsh on the left, so a reflector on the right would have evened the exposure out nicely (giving you an even overexposure a little), leaving you a little room to narrow the aperture for a better exposed, sharper shot.
Please take the above as my constructive opinion on the shot and how you could improve it. It's a good attempt and you've done well to position your son and get him to smile(ish) so just a few tweaks and it's there