I've been riding my old heavy clunker used mountain bike to work for over a year now, and am up to a good solid five days a week, rain or shine (I think it's rained on me only about four times in the last few months). Riding the new bike is an absolute world of difference! It's so much lighter and smoother that it's almost a completely different experience. As long as I continue to ride my bike daily for the next decade or so, I'll get good value out of this purchase. :)
It was pretty hot today—the temperature hit 30 C before a cold front rolled in this evening—so I didn't do more than ride the bike home. I'm looking forward to taking it to work tomorrow and giving it a good shakedown.