Google at least seems committed to open standards, which is much better than virtually any other solution. And it theoretically means it should be fairly straightforward to move your data in the future should you wish...
Exactly. For my use case (I'm a diabetic who has moved several times in the past 5 years, which means lots of different doctors) the value I gain by having access to all my records is worth the unease at having Google know SO much about me. I feel out of all the different companies trying to get into this space, I am most comfortable with Google to be the one holding my data.