Just got my Sigelei 20W in on Saturday. Didn't open it until this morning. Popped an 18650 in and away I went. NO learning curve.
I found the menu very easy to get use to and navigate.
Pros and cons have already been discussed. Going back to 10W after battery change. Menu going dark when not firing. Etc.
I freaking love this thing. I just picked up an SVD about a month ago to replace a VTR. The 510 threads stripped on the VTR and I was forced to use the stovepipe extension tube. Grabbed the SVD as a fast replacement. Was never very happy with it. Button is mushy. Didn't like the fire button being on the other side of the display. Etc.
The Sigelei 20W is a little thicker than my SVD, but not quite as tall. Very solid. The extra girth makes a PT2/Aerotank look a little small but not too bad.
The 20W (so far) is a DREAM. I love it. Solid, nothing cheap. Button feels good. Battery cap screws on with no squeaking. Stylish. Easy to use. And a REAL PRODUCER.
I love having a battery 'meter'. Excellent!!
I also picked up a Seven 22. Can't wait for the 26500s to charge so I can give it a run too!