Not property ownership, but a business partnership experience to share.
My DH set up a small IT company with his best friend. Was awesome for a while, but by the end it sucked big time, and the friendship was dead long before we disentangled ourselves from the company (at a profit to ourselves, money-wise, as the business was a success, but we'd never do it again).
In hind-sight, it would have been better for one person to be the company, and the other person an employee. Much more clear in terms of liability etc.
But the biggest thing we learned is to never, ever go into a monetary arrangement with someone without having all the various termination circumstances agreed upon.
for example, in real-estate, the clauses might go something like:
1. In event either person wants out, their share is offered to the other partner to purchase at market/retail/agreed value (specify!).
2. If partner is unable to buy them out, the whole property is sold on open market and proceeds divided evenly.
You would also need a clear and obvious way to decide how much equity each of you has in the property - if one is contributing more hours to the project that needs to be 'billable' somehow. The other partner also needs to be protected against lazy or just plain inefficient make-work that is invented to look like hours being spent on the property!
Personally, I would say that if you have the money to do it yourself, buy the property in your own name only. Your friend can be a tenant/boarder/lodger and pay rent, and also do handyman stuff which you pay him a fair rate for (either hourly, or per job).
This is an uncomplicated arrangement, with no hand-wavy chasm of undefined nature for your money to disappear into.
You just never know what the future will hold for either of you - ill parents requiring you to relocate, un-turn-downable job offer that sucks up 80 hours a week (so no handyman work being done), relationships beginning/ending/developing that necessitate different living arrangements, market crash meaning you're stuck with the house for a few years longer than you plan, someone (god forbid) dies or becomes really ill... the list is endless, but the less entangled your business affairs are, the easier it is to sort out under pressure (and the end of a business relationship is ALWAYS pressured).