We recently ported our app HeyTell from iPhone to Android, and found that we gained a little perspective in the process. Because it uses a large number of system features (native widgets, location, database, audio, network services), porting the app really required a deep understanding of each platform.
A great way to get an understanding of the strengths and weaknesses of any software platform is to port software from one platform to another. For example, in the early days of my programming life, I'd write a simple "Missile Command" game to get a feel for a specific platform.
Here are some of the various perspectives of the iOS and Android platforms, and how we view them differently after the port:
User Interface - iOS has the benefit of being based on a mature UI framework (Cocoa) and Android has had to play catch-up with features (like animated views). iOS has the edge here with some features -- table/list views in particular are much more full-featured, if a bit difficult at times. Interface Builder also is much more slick than anything available on Android (I just edit the XML files directly on Android), so I'd say iOS wins this one.
Application Framework - Android and iPhone have very different ways of looking at the world. Android tries to model an app as a loosely-coupled set of Services, Activities, and Content Providers, while iOS sandboxes each app like a traditional OS. I understand the rationale behind Android's design, but I think it confuses more than it delivers.
Performance - We've never had serious problems with performance, although iOS seems to have a snappier UI in general and do a better job with compositing and animation. Both platforms allow native code (Android via the NDK) for CPU-intensive code.
Language - Objective C does seem to have a steep learning curve and a lot of new concepts compared with Java - especially regarding memory management. However, if you look under the surface, Android has many of the same issues (look up "android memory leaks weak references"). But if you're experienced in Java, you'll have a lot fewer hurdles with things like threading on Android.
Third-Party Libraries - There are roughly equal numbers of iOS and Android libraries on GitHub, for instance. On iOS, you have easy access to any C/C++ library (without going through JNI), while on Android, you have easy access to the thousands of native Java libs. I'd say this one is a tie.
Development Tools - Eclipse is a great environment and is perfectly optimized for Java programming. XCode isn't bad either, and the experience is a bit more polished. I do really appreciate the command-line tools like adb you get on Android, however. My partner is a big fan of the Dalvik Debug Monitor Server (DDMS).
Documentation - Apple has great documentation, and you can find pretty much anything you want to know there or in its example code. The Android docs are not quite as comprehensive, IMHO. We do use Google Code Search to search the Android code base ourselves, which is very helpful at times. But you're going to spend a lot of time on Stack Overflow, no matter what you pick. :)
Market - One feature of the Android Market is that you can push an update at any time without review. This is really comforting from a developer's standpoint (maybe not so much from a user's, but we're happy about it). Android also lets users comment on their stack traces, which is really neat. Okay, sometimes the comments are not so nice, but often they add steps to reproduce - this is really helpful, especially when it seems like we see a new piece of handset hardware appear in our matrix every day and testing across all devices/OSes/firmware revisions/carriers/whizzbang modded ROMs on Android is unfortunately really tricky for a small, bootstrapped team.
Monetization - Because HeyTell is free, we don't have any perspective on pay vs. non-pay apps on either platform, but Apple's In App Purchase capability has served us well. In App purchases are really important for us, because not all users want or need all features, and we don't want to charge users for features they don't want or need. Our fingers are crossed that Google adds an IAP capability soon. In addition, on the advertising side, there really isn't anything on Android quite as turn-key as Apple's iAd. All points go to iOS here, at least for now.