Wrt build quality, I have no complaints. It's work wear and not a fashion statement. It's also a pretty old brand/businnes that's yet to be discovered by hipsters, so ... so far so good. I wear the same coverall (day after day except for laundry day ... and visits/visiting ... and podcasts) between November and April with one full-cover layer beneath it, generally either long underwear or another thin layer like old dress shirts or light exercise pants. This also means I need to wash the coverall much less often. About the same rate as average people wash their overcoats.
Also retail is about 50-60% of MSRP. I paid $70ish for my coveralls. Admittedly more than my entire bathroom renovation, but still
WRT warmth, it's important
not to buy too warm. I made that mistake when I first bought their Irontuff coveralls. The issue with this largely non-layered system is that it's warm enough to block/retain all your internal heat. This means if you pick the wrong insulation level, it will be really warm on the inside yet cold on the outside (hands, head, feet) which is rather uncomfortable. The official website temp rating are for an active worker. If you sit on your ass like me, add 40-50F to the active-ratings.
The coveralls I have had zippers running all the way up to the hips. This makes ventilation very flexible. I can leave a lot of it open to cool down for e.g. thermogenesis. Overheating is really my biggest problem.
I do wish that they'd make them in 100% cotton or some other natural fiber and adhere to a more cosmonautish design like the coolerwear line that DW is sporting. That'd be perfect.
PS: One cool (ha!) feature is that I don't have to change clothes to go outside as long as the temperature remains somewhere between 20 and 60F. I only change my shoes whenever I got out

Sorry for using Freedom units on you. I guess I've been sufficiently assimilated by now.