i love this camera. it has taken me from oldtime 35mm film novice to full time pro. i know that sounds a bit far out but its true ... with a little inside help :-)
however the 10d follows me on all my shoots be they corporate - lifestyle or just stock. it has its limits but you can work round these.
as with all dslr's dust is the biggest problem but once you know how to deal with this its ok.
the write speed sucks and has left me a little red faced on a recent shoot and the 1.6 sucks for landscapes.
that said this is a great little workhorse for me and i will keep it as backup when i get a 1ds.
i had a guy with a 1d II assisting me and our results was not to far apart when it came to what matters.
my own view is forget the 1d, keep the 10d and buy some good glass.