The Tamron 28-75mm f/2.8?

How is this lens to be used as a everyday lens. I see myself using this for some portrait work too. How is the sharpness of the photos with this lens?

I own a Tamron 28-75 f/2.8 and Canon L 24-70 f/2.8. I've been using them on a 5D and 5DII.

Sharpness: On the 5D I cannot a difference in sharpness between the two looking at 100% magnification and 20"x30" prints. Even at f/2.8 both are extremely sharp. On the 5DII I can see that the Tamron is slightly softer at f/2.8 when pixel peeping, but I still can't see a difference in large prints. By f/4 this disappears. The Canon has wicked field curvature. Because of this I almost always choose the Tamron when photographing groups.

Bokeh: Very similar. In the test shots I thought the Tamron looked a tiny bit smoother, but I've been using both lenses for years, and I've seen good and bad bokeh from both lenses. Most of the time I'm satisfied with either. Nothing special.

AF: The Canon is silent. The Tamron has a quiet whirring noise. I shoot a lot of low light weddings and live music shows, and I don't notice a difference in AF speed or accuracy. I only shoot on single shot AF, and always use the center AF point.

Build: The Tamron is built like a typical, nice, plastic lens. The Canon obviously has a lot more metal involved. The Canon should be more weatherproof. I've only been out in light rain and snow, but never had problems with either lens. I prefer holding the Tamron. It seems like half the size and weight. After shooting with the Tamron for about a year it did break an internal part through normal use. The warranty is 6 years, and it was repaired quickly and for free. I've been using it 4+ years since the repair with no trouble.

Flare: The Canon flares more easily. I always use hoods.

Comparing test shots done in the same lighting it seems to me that the Tamron is actually 1/3rd stop brighter at a given aperture.

In the end I think both lenses are very good lenses. I'm happier with the $500 Tamron than I am with the $1400 Canon. In my photography I don't see the $900 difference.

28-75 on 35mm format is a good all around lens, and does fine for portraits. On APS-C it would be good for portraits. I'd prefer something wider for an all around lens though. I like 17-50-ish on APS-C.