If you're new to Shadowrun then you're probably unfamiliar with some of our "usual" campaign book formats. The most "traditional" format we publish are
story-arc campaign books which are divided into chapters each of which is a full-blown "canned adventure" that is intended to be played sequentially to tell a single story. The next format is what we call
tracked campaigns these provide copious setting context and campaign information, but instead of blow-by-blow adventures, they present suggest a number of adventure outlines/frameworks that move the plot forward but leave the work of developing the specifics and coming up with stats to the gamemaster (making them easier to adapt to different groups' styles of play and power levels). Finally, we published
event books, similar to
tracked campaigns in some ways, these describe major events, their ramifications in the setting and upon PCs, the main actors involved, etc. They typically provide a lot of In Character setting information that is intended to function as plot devices and adventure seeds. This comes at the cost of a step-by-step adventure walkthrough that you find in many campaign and adventure products.
With
SR4, we're trying out some new tricks.
Emergence combines the "track campaign" format and the "event book" format. It presents what we usually call a "campaign framework" which establishes the overaching events that take place in 2070, surrounding the emergence of first Technomancers and later AIs into the public realm. It may be off putting to some one new to the game but many of those events are introduced through fiction pieces rather than as game information. However, each chapter is wrapped up by a Game Information section which suggests how you can use the contents of the fiction in your own game, provides a synopsis of events during the relevant timeframe, profiles the major players involved in the action, and finally provides a couple of "adventure frameworks" (outlines of adventures) that plug into the overall events and that can be plugged into pretty much any game.
Emergence is also tricky because it focuses on a couple of entirely new elements to this 20-year old setting - ones that needed further development after being introduced in the
SR4 core rulebook.
If you're looking for an easier learning curve and an adventure with a more traditional step by step breakdown (and some useful aids directed at new gamemasters) then I suggest you try the
SR4 introductory adventure:
On The Run.
The free
Shadowrun: Missions adventures also come together to present a good introductory, street-level campaign that eases newcomers into the setting and some of its peculiarities.