I felt compelled to write a review because this lens seems to get a bad rap.
The range is great. 28-105. On a crop camera it is good for general shooting like portraits or events. Focus is slower than a USM, but it is very precise and quiet for a non-canon product. Focussing manually works very well.
2.8 is soft, but the lens sharpens up as you stop down. It is not the sharpest tool in the shed--certainly not canon L sharp, but it is better than many consumer-grade zooms.
It has a pretty good macro capability too.
Yes, this lens is heavy and due to its 82mm front and prone to flare. 82 mm filters aren't a problem--EBAY! The anti-slip works well, and the build quality is pretty good with little or no play or wobble.
Overall for general shooting, this is a pretty nice lens for the range it covers and the price you can get it for. You can't compare this lens to say a 28-70mm 2.8 L or a 24-105mm f4 L . They cost 3-4 times as much. Yes, they are better lenses, but this is the only 28-105mm 2.8 ever made.
If you find one for 150-300$, try it. I have mostly canon lenses and have never been a big advocate of aftermarket products. But this lens, along with Tamrons 28-75mm 2.8 and 17-50 2.8 are pretty good. The latter 2 offer better sharpness, but less range.
One thing you might find though is that for some reason, the 20D with a 580 EXII flash is sometimes quirky with exposure with all 3 tamrons listed. Most of the time, everything works great. But keep checking your preview screen just in case.
Yes, I would recomend this lens. I wouldn't use it as a sports lens or for something which I need a super-sharp tack driver, but for general shooting and at a low price--it is pretty good.