Is there any bonus towards your spouse now? Seems like there should be *something*...
The thing is, there might be nothing.
-Children, incapable characters and prisoners can no longer join factions
Wouldn't a steward ruling in the name of an incapable ruler decide over the political actions of the state? Same thing goes for prisoners and children, though it should be limited as the child grows older.
-Constructing baronies now makes the barony a vassal to the county holder instead of the builder
Why? If I build a castle, it's my castle unless I specifically give it away to someone which would improve my relations with him. The way it is is the way to go.
Everything else sounds pretty awesome.