Not all expansions actually improve games. This is the best game expansion I have come across and gives PANDEMIC a whole new dimension. The original game is a lot of fun but can become repetitive after several plays..you only really vary the number of Epidemic Cards. ON THE BRINK means you can blend in aspects of the original PANDEMIC with the variants. For example, the 'Virulent Strain' epidemic cards, where one disease behaves differently and more threateningly than the others is a great idea in its own right. For variety, you can mix them in with some of original green epidemic cards or add other new factors. In short, the expansion gives you a huge repertoire or variety of game in content and difficulty with other new ideas like the Bio Terrorist and a 5th Purple disease to explore too.
Other things I like... the smaller playing pieces are an improvement, the Petri dishes to hold the disease cubes give the game a scientific stylishness, and being able to name each disease on the lid of the dish is fun.The 6 new player roles are well thought out. There are some blank cards too for you to add new roles or Special Abilities. All in all, if you like PANDEMIC, you'll love this!