I'm very glad that I took a chance on this thermal top.  Other thermals I've tried were not much better than regular shirts at keeping me warm and this is very very warm.  I'm usually the coldest person in any group and originally purchased this for a trip to the Yukon but it's become a regularly worn item. I find that in 30-40 degree weather this top is fine by itself under a warm coat.  Normally I'll wear a base layer and a thick hoodie or heavy sweater under my coat.  This top lets me get rid of all that extra bulk.  Luckily, it's also got a cute fit because when I have worn this with a layer over it usually gets too warm to wear indoors for long.  It is definitely a casual top and it has started to pill a little bit (however that may be due to the type of lining in my jacket which is known to cause pilling) so I wouldn't wear it to a nice restaurant or anything.  But I have worn it to less dressy places and out shopping.  As far as comfort this is a soft but thick and very snug top with stretch.  The seams don't itch and the neckline is comfortable despite being a thick jewel neck (close to neck).  I'm also thrilled that it's not too long on me.  I'm 5' 1.5" so I run into problems with shirts being too long but this one goes just to the top of my hip.  It's perfect for preventing back draft without looking too long.  I ordered a small which is perfect for me (111 lbs., 34C) though out of the package I worried it'd shrink after washing and become too small but it has been fine dried on low heat through many washings.