Using a Twixtor plug-in in FCP

I recently saw a video where someone used twixtor to get super smooth slow motion in their video. I downloaded a demo version because i wanted to give it a try before i considered buying it but I could not get very good results. When i apply the twixtor filter i slow it down to about 40-50% and the video looks very blurry and just not as crisp as other clips ive seen. Any Advice on the best settings for the twixtor plug in, final cut, camera settings?
Film speeds, etc.
Thanks!
Bryan