Personally I don't like Trek. I don't like the way they handle, or feel in general. However if it works for your girlfriend - great. She's the one that has to ride it not me.
Trek's bikes are (for the most part) on par with the rest of the good players in the industry no better no worse than say a Specialized, and other than the occasional warranty issue I can't say I've heard a bad thing from Trek owners.
ithink one of the main reasons people hate Tek is due to the fact that people who know jack**** about bikes "know" that "Trek has to be the best 'cause that Lance guy rides one in the Tour Duh France" It's those people that cause a lot of the backlash.