I tried this on my wrinkled dress, on the left side in the photos. It took quite a bit longer than I thought it would. The next morning I decided to try the steam feature on my Hamilton Beach steam iron. The results are in second photo. Left side, hand held steamer, Right side, steam iron. Both in upright position. Hand held did do better job. 
I couldn’t locate any mark for minimum fill. It is a little difficult with my diminished hand strength. Overall I do like it, and will experiment on my crochet and knit projects that require stretching.