It's very fast. It loads fast, the interface is fast and the navigation is good. It finally found out that my home is not 5 towns and 5 miles away.
So I started using it again, to and from work to see traffic. That seems to work OK as well.
Then I tried today doing a "fake" (not needed) navigation to a business and it sent me to the wrong place. This was just a test. I knew where the business was located and Apple doesn't. Yes I reported it.
And that's the rub. It's either/or. I can't really trust maps to get me somewhere I've never been so back to MotionX GPS.
And yes, Apple should allow you to choose the default map app. At least until the general consensus is that their map app works nearly perfectly. It's far from that, IMO.