The bottom line: The GORE Windstopper Baselayer Sleeveless Shirt isn't as warm as advertised, but it is a fantastic, mesh-lined tank top for hiking or trail running on warm, sunny days when proper ventilation is crucial.
The GORE Women's Windstopper Baselayer S/L Shirt is a high-quality, technical piece of clothing that anyone who's really into trail running or hard, uphill training hikes on sunny days will want in their wardrobe. The quick-dry fabric and mesh back will keep you cool when you get sweaty and still have a ton of miles to crush as you navigate your favorite trail.
Strangely, this piece of gear is being marketed as a baselayer to add warmth and wind protection to a cold-weather outfit without adding bulky fabric. However, if making a windproof garment was GORE's aim, why would they make the entire back of the garment out of mesh rather than having ventilating mesh side panels instead? I tried this garment while hiking with a thermal baselayer worn over it, and I found it to be similarly warm as simply wearing the long sleeve baselayer by itself.
That being said, this is a high-quality, well-constructed garment with flat-lock seams, moisture wicking, and a reflective GORE logo on the front that makes it a perfect addition to a spring/summer/fall trail runner's wardrobe. The mesh back really helps with moisture and heat management when things get sweaty!
As for fit, the GORE Windstopper S/L Shirt is designed for a "next to skin" feel, which means it hugs your body. Because of this, I would not recommend it for women with a larger bust area (or perhaps buy it a size up!).
At the end of the day, I look forward to wearing the GORE Windstopper tank on the trail for years to come, just not for the reasons intended in its design. I'll be crushing big, uphill miles in this shirt on sunny days when I want a reflective mesh shirt to protect my skin!