The graphics are ok but not exactly an improvement over CFS2. CFS3 out of the box is riddled with bugs so you get the update which is a must and then you realize that there is still no joy.
I could never immerse myself as deeply as I could in CFS2. I also prefer the type of Training Missions available in CFS2 especially the carrier landings. You nail those on a regular basis and you won't have any problems landing any aircraft in FS.
Finally compatibility. In CFS3 Microsoft used a different engine which made it pretty much impossible to import aircraft from other sims. I used to export all my aircraft from CFS2 to FS2002, both the default a/c as well as all the payware a/c, even the smaller default a/c from FS2002 would work perfectly all right in CFS2... for instance, I took the default Sopwith Camel straight out of FS2002 and flew it in CFS2 where it suddenly had guns
So I figured I try a carrier landing in the Camel and after botching the approach several times I thought I'll shoot at the carrier and see what happens. I did manage to sink the carrier after half a dozen strafing runs but not without drawing plenty of flak in the process.
I know this is not realistic, but I choose to use any flightsim, both combat and none-combat as a platform for my personal enjoyment. In this light, CFS3 is just too limited for my taste.