I have a pretty successful Android app on the market and I've been working on the iPhone version for a month or so now, getting it ready for submission to Apple.
So I would definitely pursue both platforms.
The publishing process is certainly much easier for Android, but aside from that they are similar environments, despite the different languages involved (Objective-C vs Java).
As an experienced Java developer I was a bit resistant to learning Objective-C at first, but once I dove in, it turns out its pretty easy. Probably easier going from Java to Objective-C than the other way around, but hard to say for sure.
Don't forget about design. Probably the hardest thing about app development is the design (look and feel), not the code. The code is easy. Making it look good and deliver a great user experience is difficult (at least for programmer types). So make sure you have a good designer to work with, otherwise all the great code will go to waste.
I spent a bit more time worrying about design for the iPhone version, in part because of fears of being rejected for not following Apple's UI guidelines. So make sure you read those up front, and follow the patterns that Apple uses and suggests.