My company has been a Big Business user for many, many years now - Client/Server version with 10 users. I've gone through many versions of this program as it's been updated over the years.
Granted, the UI is not what we would all like. Beyond that...
1) The tech support is awesome!
2) I've suggested numerous feature requests which have been incorporated, making my life easier.
3) BB regularly puts out updates, fixing problems and adding features.
4) It's simple enough to run and support that I can do it.
5) For a client/server program, the price is great. There was absolutely nothing close when we first got started with it.
6) Did I say tech support was awesome? It is. Try getting a two hour (or less) turnaround tech support phone call from Quicken.