Originally I was going to make my own adventure to put my friends through, but then I realized that when I try creating a world I tend to go overboard. Way overboard. From what I had so far, the characters would: make a treaty with the kobolds, help them in their war with the goblins, and eventually they would fight the world's ultimate evil: Gnomes. Despite all the improvements 4th edition made to DMing, I still felt like this was going to be a monumental task... So I decided I would use a pre-made adventure.
The first adventure, H1 Keep on the Shadowfell, was released before the core rulebooks (The Dungeon master's Guide, the monster manual, and the player's handbook) and had a shortened rule book, which helps since I haven't been able to save up enough to get all the books yet. The adventure has all that you need to get the characters (premade ones that come with the adventure or ones that the players made themselves) from the first level to the third. Monsters, their tactics, and their items are all described, and maps for the encounters are included. To think I was going to do all that work by myself.
The 4th edition comes with plenty of content to place into your own adventure, but for a new GM like myself, I recommend using the premade adventure. Everything may be there already, but that does not mean I have to stick to it exactly, why call them cultists when "death eaters" always gives the players a quick laugh? Considering that the players in my group are split into two groups right now, it seems I may get to get a bit creative. Monsters need to beware Moblin Firebeard, the dwarf sorcerer, an NPC not included in any premade adventure.
Now that I have played through a session as DM, not that we got very far, I have found my favorite thing about 4th edition: Minions. Minions are exactly what they sound like, cannon fodder. They take one hit to dispatch, making them useful to fill an encounter while not making the enemy force too powerful. they are so easy to kill, in fact, that they probably don't like to go out on windy days, for fear of their lives. To really put it into perspective, remember the putty patrol from the original Power Rangers? Those are 4th edition minions. One hit and they are gone.
My only problem with them is that some of their attacks have set values, so how does that work with the new critical damage system? Normally you would use the maximum value of the dice you would roll and use that as damage, but it doesn't really make much difference when it it just a 4 damage hit. It broke my heart to have to tell that poor little kobold that his critical hit did normal damage... I'll give him a magic item or something to make up for it when he comes back to fight during the next session.