I'm just curious what features you find missing. I only use it for personal use, but it has everything I need. I generally read in the OFX files from my credit cards / bank accounts and it's pretty smart remembering old purchases to put them in the right expense accounts. It takes care of my loans, stock prices, expense reports, budgeting, etc. I even do some pretty advanced stuff with the database file directly and having easy access to the data makes GnuCash pretty useful to me.Sadly, GnuCash is still rather rudimentary and doesn't meet the needs for most business professionals. When checking out GnuCash 2.4, I'm still much better off using Intuit's proprietary web-based products paired with a spreadsheet or text file than this open-source accounting software package as Intuit's software is much more useful and complete.
Now like I said I don't run a business, so I'd be interested in what you have to say. At least from a personal finance perspective, I would sat GnuCash is very mature.