I've had a joint account with the gf since we first lived together. Had our own accounts, and set up a standing order into for about 75% of our salaries into the joint account. Got to the point where if the joint account was running low, whoever had the most money would top it up.
Since then (8 years ago), we've moved over to getting our salaries paid directly into the joint account, still have our own accounts but they are pretty much dormant. The only downside is its impossible to transfer money out for presents/gifts etc as we can both see everything. Plus side is if she wants to get married, its going to be a joint saving up thing. For a couple of months earlier this year, each time I had some spare cash, I'd plan to open a seperate savings account to start saving for 'the big day' but then she'd remember I had £30 cash and ask for it so she could pay for something, so in the end I just came clean and told her we'd have to save up together 🙂