There was once a time where the men of Gondor would make the pilgrimage out to forest of Fangorn to commune with the treefolk...
Ok, maybe that's not canon, but it makes for a good deck! Gondor excels at resource generation, while Ents are econmically efficient. Together, they make a deck which should be able to put units out at a good tick. Denethor is here simply to push resources to Faramir and Beregond, and pay for the few cards in the deck. Once Steward of Gondor is out (which should go on Faramir), more than likely, each turn you'll be passing his resource to Beregond. Put Gondorian Fire on Faramir and he should be able to handle most foes.
The weakness of the deck will definitely be in questing. With only 3 on the heroes, and most allies coming into play exhausted, it can be very daunting if used solo. On the other hand, if taken on a siege quest, you will have a strong start.
There are a variety of cards in the sideboard, based on what type of quest you come across. Cards such as Behind Strong Walls and Gondorian Discipline are in their for quests which are heavy on attacks, where you need to make sure that Beregond is available. When playing multiplayer, ask your partner(s) to include copies of Unexpected Courage and share Beregond's defense around the table.