This is a somewhat belated reply, but yes, I use Gnucash.

It's the only personal finance software that I've used, so I can't compare it to Quicken or MS Money. I manage all of my bank, credit card, insurance, and investment accounts with it. I have data going all the way back to 2000 stored in it.

I only have a couple of complaints about it. It does not properly calculate the investment return from DRIPs unless you use a convoluted way of entering the DRIPs into your account. It also can't get TIAA-CREF online quotes because the online quote module is a little out of date. I have no trouble getting online quotes for any other securities, though. And many of the built-in financial charts are lacking in some features.

However, these drawbacks are far outweighed by the benefit of never having to boot into Windows to manage my finances.

--Mike