As a widget-type app, OMWeather is great and I like how it's always available right there on the desktop. Using MyCast as an example to compare to however, it lacks a number of things.

No GPS support.
No severe weather alerts.
No severe weather info.
No radar loops.
No informational maps such as windspeed, dew points, lightning strikes, etc...

Pilot MyCast goes even further by adding a number of items pilots need such as raw metar and taf data, wind speeds aloft, icing and turbulence maps, etc