I have a NatureMill, too.
Does the scrap bucket in the kitchen attract (fruit)flies?
Not necessarily. We use an open bowl in the kitchen that most food scraps go in to (except meat or fish or dairy). It gets emptied into the NatureMill on the patio every three or four days. If you live in hot climate though, things may be different.
Does it smell?
Sometimes. Apart from the general information about items to be avoided as described in the manual (RTFM, really), the two things I found that cause smell are too much acidity (e.g. citrus fruit) and too much moisture.
Saw Dust Pellets?
Using a lot of fresh ingredients that contain water naturally, I end up needing way more sawdust pellets than I expected I'd need, to the point where I wonder how much compost I could buy in the store for the amount of money that one pack of pellets costs, and put that in relation to how much compost one pack of pellets yields. As I only use the device for pre-curing in an apartment (I collect the output in a home depot bucket, and then take that to a real compost pile to continue its process for another year) - i found that dry rice is a cheap and available alternative to sawdust pellets. However, they also come out on the other end, undigested if you will. it remains to be seen how well they decompose in the real compost pile.
A bit. Having the composter near your bedroom window definitely won't help with a good night sleep, but it isn't too bad, either.
Would I buy the composter again?
I don't think so. But as long as I have it, i enjoy using it. However, there are some serious environmental and financial concerns, namely the sawdust pellets (shipping, production, packaging, cost) and the recyclability of the device itself (it's pretty much completely styrofoam, a lot of people reported defective units that can't be repaired, and folks who realize after purchase that it isn't for them).
One day I'll have my own yard and a normal compost pile. I'm looking forward to that day.