1) Photo Editor Mode2) Weekly Challenges
3) 50 Normal Challenges
4) 26 Human Skins
5) Concept Art
6) 225 Feats!
7) 9 New, Free Trophies
This is ALL FREE and can be played right now!
The first thing to note is that you now have a rank! Start at level 1, gain CP to rank up, and unlock new challenges, and presumably new human skins (comes with their own in-game sound effect), and other content (like concept art) through ranking up.
WEEKLY CHALLENGES
Basically, Housemarque gives you a challenge to complete every week like "Get high score on this level, but you can only move right", "Get high score on this level, but shooting is disabled", etc.
The higher you score, the more CP you get, with the top scores getting huge payouts.
BASIC CHALLENGES
There are about 50 of these! You unlock the rest by leveling up.
26 HUMAN SKINS
It seems you can unlock human skins, though some are already unlocked if you played the game during special days (I have a turkey for example, from thanksgiving). I assume you can unlock more as you rank up.
225 FEATS
This is a ridiculous number of missions. They range from everything you'd expect. Think of them as trophies that couldn't be included. It seems like there is always something to chase, regardless of what mode you are playing.
NEW TROPHIES
There are like 9 trophies associated with this free content, and more associated with the DLC for next week.