I actually used one for the first time in November last year...one of my customers bought one.
Are they good quality? Well as in most everything in life you generally get what you pay for. Now that being said, on 24 gauge steel it did a decent job...again, you get what you pay for but for the price it did a decent job...I found it to be quite a bit more time consuming but, if your not using it every day or trying to make a living with it...it will work.
I haven't used it enough to comment to much on depth but can see that being a problem depending on what your doing.
I also used it on 18 gauge...I'm fairly sure it was 18 gauge, 1930 Model A and it did work, it was a bit labor intensive, I could see the foot lever come in handy here, I only used the hand operated one. I just checked...it was 18 gauge.
I didn't spend a bunch of time with it, I tried it out on a scrap of 24 gauge I had laying around and then went to 18 gauge and it did work with making a piece for the Model A....If this is hobby only it's not bad...I wouldn't want to get to aggressive with it though...it is entry level.