I have worn it while walking the dog and the temp. was in the 30,s . I wore a t-shirt under it and my arms were cold and body was chilly . Another time everything was the same except for a 20 m.p.h. wind and I felt the same - no colder .
It does fit snug and its a little tight in the shoulders and upper back , the sleeves are a little long for me .
I,m 5-10 195 . It does stretch and moves with me very nicely so a large is fine but it just feels snug.
I love the way it looks and will be using it alot hiking the Adirondack 46 in N.Y.
I would say buy it , but be aware how it fits .

I actually replaced my Marmot Superhero with this jacket. It is windproof as is the Superhero, but this jacket has more pockets than a pool table (okay, only four), plus pit zips which the Superhero has none. I highly recommend this fleece. I have worn it in 10 degree weather and in weather as warm as 50* F. The only thing the Superhero had over the Heat Shield was it's zip-off hood. You cant go wrong with either, but for utility/versatility I would opt for the Heat Shield, you wont be disappointed. One note, it has an athletic fit, so expect a little less room than Marmot's shells.

I've been looking for a windstopper fleece for a while and was excited to find this one from Marmot. I'm 5'8, 160 lb with 32/33" sleeve length and I've had to pass on the Mountain Hardware WindStopper Tech Jacket because it was too short in the sleeves (I've found most of Mt Hardwear's jackets run shorter in overall length). The Heat Shield is a slightly heavier weight jacket than the Mt Hardwear, which I liked. I really like the pitzips and the 4 exterior pockets, unfortunately the sleeves were too long for me on the Heat Shield (I bought a medium), so I chose to return it. I might be nitpicking, but when the jacket is zipped all the way up the collar wasn't very close around my neck, so I while it is a windstopper jacket, I could see it being drafty around the neck, however I would have kept it if the sleeves were the right length. There's not many quality fleece windstopper jackets on the market, but I'll keep looking.

This WindStopper jacket has lived up to my expectations so far. It completely blocks out the winter Chicago winds that seem to come from every direction and it keeps the heat in great. I've layered it with an Arc'Teryx Polartec Thermal and the combo has made it more than acceptable at temps down in the teens (plus wind) without being too bulky. The neck is a bit loose with just a t-shirt underneath, but I'd rather too loose than too tight. The velcro wrists aren't the greatest, but they get the job done. With the proper laying, I'm expecting to wear this a lot throughout the year. The fit is perfect for me, too...5'6 150lbs and got a small. I could easily layer it under a hardshell for the really cold or wet days. Getting it from backcountry on sale is making it well worth it, especially considering the already great quality that Marmot delivers at prices below other brands.

Took this jacket on a trip to Lethbridge Alberta recently. Wind was a steady 70km/h, with gusts to 110km/h. Shingles were being ripped off roofs, but no wind was getting through my Heat Shield. Pit Zips helped shed heat when getting active, and cut is nicely athletic. Layers nicely under my hard shell. Totally recommended

I am swooning over my new Marmot Heat Shield. At first I had reservations that it wouldn't be warm enough, but after just getting in from a brisk -36 C, -32.8 F windy Québec City day, I can finally put my fears to rest. The jacket stood on its own against the wind and cold and I couldn't have been more comfortable. The pockets are snuggily warm with your hands being behind the windstopper material. Being 6" and with a slender build the medium fit perfectly. Like others I don't exactly see the reason for the velcro wrist straps, but I'm not complaining. During the summer I could see the jacket being a little warm, but perfect the rest of the year round.

I've been living in New Zealand for the past 3 months, and the Heat Shield stands up to everything that this landscape has put it through so far. Even in winds at sea that almost blew me over, my core stayed perfectly warm with only a T-shirt underneath. My only complaint is the velcro wrist straps - not very effective in fulfiling their purpose, they instead tend to get caught on stuff. No problem when considered with the performance of the jacket as a whole, though. XL fits 6'3" 195 lbs well.