Tried this for a year with a "friend"....it was the worst decision I've ever made. Lot's of people tried to talk me out of it, but I had to see for myself. Turns out, I think we wanted different things, even though that is not what was discussed. On the bright side, I got to know and meet a lot of dentists I wouldn't have met and I learned a lot about private practice [which was great]. You just have to get in the right practice and I've learned from my colleagues, it sometimes takes a couple to get the right fit. It is easier to do this when you are younger and don't have a lot to lose by trying out a practice for a short while to see if it is the "right one" for you. The person who described it as a marriage was right! You don't have to think exactly the same about everything, but you do have to be able to communicate well and respect each other's goals and philosophy. I also think you have to have a similar sense of ethics and financial approach. You may like your friend more in the long term if you are in different practices and you can "compare notes"....perhaps then, when you have experience, you can best plan how you might practice together. There are two dentists in my town who were in the same class and went into practice together at the same time and they have done well....I don't know of any other practice with that same scenario. They are different from each other, but the main thing that I think has let it work for them is mutual respect.
Best of luck to you!