Google Maps and Navigation is what I miss most. In fact, I think it is the only thing I miss from Android. What I especially miss is the integration among all the features, and the fact that the capabilities were all fully functional. On WP8 I've tried pretty much all the alternatives, and settled temporarily on Garmin for auto navigation, Mango Transit for transit routing, and gMaps for walk routing. These are all very different from each other, so it makes a rather klunky way to get around. And none of them work very well on my HTC 8X.
In researching this, I really grew weary of false and misleading claims made for these apps, and I am not terribly happy with any of them. The Garmin app is extremely slow, taking many seconds, sometimes a minute, to respond to a button press. Many of the buttons on the map view don't seem to do anything at all (and in some cases it's not clear what they were meant to do). However, once you get the navigation started, it works pretty well, and has some good display features. Incidentally, I complained to Garmin about the unresponsiveness of their app, and their response was that there must be something wrong with my phone, and I should go to HTC for help. They couldn't explain why none of their competitors, nor any other apps, had this problem on my phone. In short, their response was "Don't bother me."
And another informative story about Garmin: 4 years ago I bought the Garmin app for my Blackberry. It had an amusing bug where occasionally a different voice would break into the navigation script and give incorrect directions. We called the normal Garmin voice Gertrude, and called the incorrect voice "Gertrude's Evil Twin." Now today, on a whole different platform, Garmin's software still has Gertrude's Evil Twin. I wonder if they ever do any software maintenance.
VZ Navigator is also disappointing. If you visit their web site, you see descriptions and screen shots of all sorts of wonderful features. But the real app has none of the features described on the web site. It's like an entirely different program, or like the Windows Phone version is a quick port of a 5-year-old Windows CE version of the software. If you haven't yet spent money on something like Garmin, you might be just as happy with Turn-by-Turn, which is more basic but at least you get what you pay for.
Several apps claim transit support, and most of these claims are bogus. A couple of them (e.g. Garmin, Here.net) do transit routing, but don't consider the bus schedule. So they can't ensure that transfers will work, and can't tell you when you need to get to the bus stop. gMaps is even worse: it has a map layer for transit, but no transit routing at all. Fortunately Mango transit seems to work, but the routes it proposed were not always the best, and sometimes led you to take long bus rides (out to the end of the line and back) unnecessarily.
It's weird on Windows Phone that you can mark a location in the Maps app, and then pin this on your Start Screen. Then if you press the tile on the start screen, it doesn't take you back to the Maps App, but instead gives you a link to navigate to the location in VZ Navigator (if you have it). And if you decide to pin two or more locations on your start screen, you have to use a large tile size because otherwise there is no way to tell the tiles apart from each other.
So Google had its act together on navigation, but Microsoft's ecosystem is a mess at this point. Maybe at some point Nokia will produce something that doesn't look like a dog's breakfast, but the Here.net web site is pretty inadequate so I'm not holding my breath. I'm afraid that until Microsoft itself gets its act together on maps and navigation, this is going to be a major weak point in WP8.