IQ wise, I do not regret spending what I did on it
Build quality wise, I do. It feels cheaper than $880, which is what i got it for. For 9 benjamins I better be getting something quality. Also, the IS did die on me too (still need to send it in for repair). It also has the dreaded dust issue, which I thought never would happen to me.
In short, I really did love the IQ while it lasted. I didn't mind the dust, since it doesn't affect the actual imagery...but the failing IS motor was QUITE a big problem. It prevented me from focusing and taking shots. I ended up getting a 24-70 f/2.8L to cover my graduation (the 17-55 failed right before then). In the end, if you don't need the IS, get the Tamron. If you do need the IS, only turn it on when you need it. I made the mistake of keeping it on all the time...though other IS lenses are not known to fail at this rate, even when left on all the time.
It lasted me a year, and it was a good year at that, in terms of the images it produced. However, when I take stock of what it cost when I got it and what it will cost to get it fixed...I'd have much rather spent my money on a more reliable lens that would've lasted more than a year without failing.
Again, IQ worth $1000, but it's a gamble in terms of the common issues with this lens (flare, dust, failed IS).
That said, I will get it repaired and put it to good use, remembering to turn on the IS only when I need it. Hopefully it will last me until I get a FF body that will make the 24-70L a more usable wide angle. I will miss it though, since f/2.8 and IS is a winning combo in my books (I shoot a lot of low light action stuff). I'm glad I went with it as my first lens, problems aside. It was on camera about 95% of the time until it failed.