Amazing condensation of human history
With the addition of Gods and Kings spicing up early game and Brave New World adding tonnes of options to the late game, I must admit that overall experience now feels quite complete. And I can now say with much confidence that the intention of Firaxis was always to create a decent base with the Vanilla and add features on top with multitudes of DLCs and expansions. While I do not necessarily agree with their approach, it has been quite successful: both from a critical and commercial standpoint.
Brave New Worlds adds a plethora of mid and late game options to the core game play. You can now generate 'Tourism' from some of your wonders and buildings and augment it using Great Works of Writing, Art and Music. You can also commission Archaeologists to dig up antiquity sites and discover artifacts. As the power of your Tourism (they could've probably used a better word for it) grows and surpasses the Culture output of other civilizations, a Cultural victory becomes possible.
The game also introduces the World Congress (which morphs into the UN in later eras) where you can vote on game changing resolutions which can either give you a significant boost or hamper the progress of your foes. Once the UN is formed, you have a chance to attain a Diplomatic victory once you get enough votes (from in game delegates). The game manages to capture the political machinations behind the resolutions quite well even though the AI behavior still remains finicky at best.
The social policy tree has also been overhauled and gives you an option of choosing between 3 Ideologies in the mid-late game: Freedom, Autocracy and Order (aka Democracy, Fascism and Socialism). An ideology gives your civilization some unique bonuses (in the form of more policy options) which can lend themselves to particular types of victories. There are again political connotations of choosing the ideology and your relations with other leaders will be influenced by their own leanings.
All of these features add a very interesting element of strategy to the gameplay and ensure that winning the game in an entirely peaceful manner is no longer a boring proposition.
I still have some qualms with the essential gameplay elements and I feel that the devs could have done a lot more with the expansion packs than they have. But with the addition of this new expansion pack, Civilization V can finally be called a worthy successor to Civilization IV!