Interesting conclusion from a recent DataMonitor report as follows:
Datamonitor believes the .NET CF is best positioned for success in the next 12-18 months. Compared to J2ME, .NET CF lacks complexity, is integrated across all aspects of Microsoft's solution & enables solutions with superior functionality (though Microsoft's fixed-line heritage sometimes make mobile application development somewhat problematic).
Report is available here: http://shrinkster.com/3nr