Sounds about right for the price of that lens. I had one, and loved it when I had it paired with with my xti. It suited my amateur needs just fine. However, as I started to get more advanced, I quickly started noticing its limitations (lack of sharpness, saturation, SLOW focus, awful in low light). I upgraded to the 70-200 f4L and I still love and use it today. The only drawback of the 70-200 was that I caught the "L disease" with it being my first L lens. I now own all L lenses (save the 50 1.4) and shoot with one-series bodies.
In good light it's fine, and if you don't do paid work or pixel peep and just want a lens that will get you in close, buy and enjoy it. It's a fun lens to have.