Tamron 70–300mm f/4–5.6: Great cheap lens, but choppy bokeh.

The Tamron 70–300mm f/4–5.6 Di LD MACRO 1:2, to give it its rather unwieldy full name, is a wonderful lens for a very bargain price: only about $150 street, for a lens that's really quite impressively sharp, rendering very fine detail, and with good color reproduction besides. Take it from me, you will be blown away comparing it to your kit lens—I was—or, for that matter, to your camera maker of choice's budget 75-200+ offering, for less money than that lens too. It also stays at f/4 for longer—not dropping to f/4.5 until 135mm.

Of course, you don't get perfection for only $150. (It could be argued that you don't get perfection for $1,500 either; lenses are by their nature compromised to greater or lesser degree).

The bokeh wide open is a little compromised; it's bright-ringed around the outside of the out-of-focus circle, which makes the overall look of the bokeh a little choppy:



The objectionability depends on the nature of the background, of course; here, the second image blends together much better.

Stopped down, though, the bokeh improves.

The other issue is chromatic aberration on specular highlights, which is obvious but not objectionably so IMO; others might disagree.