I think I would tend to avoid buying a rental home with a partner. If you can't afford it yourself, then you
truly can't afford to own one! They're VERY expensive to maintain. Most homes run at a loss. You have no idea how much work and effort goes into it, like hours, every single day! (I wasn't prepared for this part).
Don't do the work, you won't get bookings.
How do you split up the work load amongst partners? How do you decide what to spend $$ on for the home? (This is important!) Maintenance is expensive, and since it's a rental home, it will take a lot more wear and tear than a normal home, meaning more maintenance, more replacement of items, etc.
I think it's a great tip to plan on being able to "carry" the home for 12 months if you don't have rental income. Will you be good at marketing it, running it, getting bookings, decorating it, setting up a website, etc? Hard to say, it's not impossible, but it's definitely a ton of work.
Here's an article from the WSJ:
http://online.wsj.com/article/SB120232437161848343.html
Here's an interesting article posted on another owner's website about vacation homes:
http://www.mickeytown.com/how-do-you-recommend-that-i-furnish-and-decorate-my-vacation-rental-home/
I also suggest doing some reading on:
www.laymyhat.com