Rule is filter and symbolizer, style is collection of rules
Expression literal
Symbolizers with method for creating literals
Renaming literals
Provides for tests
Allow instanceof checks for geometries
Treating geometry as just another attribute

The first set geometry is considered the default.  As an added bonus, we're back to a single argument constructor.  Later, we could allow a schema to be set.  This would be done before setting values (calling constructor with no args).