I have this stem on all my bikes. It is well made and stiff enough for me. I am 6 feet tall and 205 lbs. I ride about 6000 miles a year. I have never had any issues with this stem.
Stiff and inexpensive. The cutout edges in the steerer clamp are rather sharp and can scratch carbon steerers. Not lightweight but that's why it's stiff and inexpensive. The bar clamp is a bit wide so if you're using clamp-on aerobars you will not be able to set them up as narrow as compared to a ritchey wcs for example.
I put this stem along with their matching flat handle bar on a single speed bike. It looks good and fits the project perfectly. I would recommend this product to anyone.