The big thing with this program is to spend some time tuning it. I have found that 105 degrees is max for a 4:3 monitor, I think about 120 degrees will be max for widescreen. If you use 150 degrees, of course you will have distortion and the view will be screwed up. It's like everything else in life, you need to use it in moderation. The best thing is what Squawk noticed, you get a more realistic field of view. It should almost be imperceptible, especially with a std 4:3 monitor, With a 16:9 or 16:10 monitor, you can get a nearly full field of view as you see every day with your natural eyesight (assuming you actually use your full FOV), again that will be about 120 degrees max.
P.S. I have had quite a bit of trouble with the button assignments. The good news is it works great with a slider or rotary. Also two VERY important points, you must disable all zoom assignments in game and also disable the "z" axis on your track IR because both will interfere with it.