I'm an advocate of marriage meaning together in everything.
Sometimes even work. But i've had some trouble finding a "Personal" finance app that would allow me to make shared budgeting and allow input from several users.
It's somewhat like a google docs stuff for finance. I've been using doodle spreadsheets since shareability with my wife is the utmost important feature.
We use mint for just that. We have a "shared" account. We each have the mobile app and share the same pin for the application (not our phones -- you can set a pin in the settings on the application).
Thus we each share a login to the site, where we have setup all of our accounts. In the "Your Profile" link at the top of the page, you may select the Email & Alerts option. From here you may add a second e-mail account. This way if you go over a budget or have a bill upcoming each of you will get a notification.
We have setup budgeting through the web site, and either of us can modify the budget via logging in.
We use YNAB to handle our household budget - their latest version allows cloud sync between Android/iOS devices and various desktop installs. I have the budget folder shared with my wife's Dropbox account so we both an view the budget, enter spending, and make changes.
The best solution I've been able to find for this is MoneyWiz, where both are logged into the same sync account.
