Excellent. Love it. Obviously bonuses are removed if you unclaim or lose all buildings inside your area.
Lets people base almost anywhere, encourages teamwork (seeing more bases are viable if you chain) or to just build next to someone else to cover one exit and take the bonus from somewhere nearby!
We might need some suggestions of more bonuses. here's a list i came up with:
More damage to your units/towers
Less damage from all enemies
less damage from bosses only.
Improved lumber generation (can be done in several ways, in some bases possibly even go as far as double income?! otherwise 1 in x chance that you get bonus lumber when you produce lumber)
Bonus experience for heroes who kill units from inside the base.
Extra vision around you base
Allied units spawn inside your base (i'd suggest adding an unbuildable "spawn point" to a base which has this)
Too some weaker ones such as: Reveals invis units, 2 gold added for surviving 10 minutes inside base. +1 armor aura.