I think that sounds like a great system, if you are both in agreement. We decided to do partially joint finances as well, and it has worked out brilliantly.
We both pay into a joint account every month. This was originally a percentage of both of our salaries when I was earning more, but now that we both earn the same, we contribute the same. Out of this comes our mortgage payments, our groceries, insurance, household bills, and any purchases for the flat.
We both have our own cash ISAs, but these are considered joint savings. We also each pay into a travel account, out of which we pay for our holidays every year.
And finally, we both keep separate current accounts. We are both paid into our own current accounts, and whatever is left in these after money is transferred into our savings and joint accounts is considered our own money. DH tends to spend money on music and dvds, and the odd expensive nights out with his friends. I tend to spend money on clothes and expensive shoes for my deformed gimpy feet and lunches/evenings out with my friends. We decided we didn't want to have to ask permission to treat ourselves, and we wanted to avoid the possibility of feeling resentful over how we each spent our extra cash. We've never had a money-related argument, so it's worked out fine for us.
My mother thinks having separate money is being selfish, but I think it's the best system for us.