We've come a long, long, way from "Roll 3d6 6 times." While character creation in Dungeons & Dragons Fourth Edition is somewhat less intricate than it was in Third Edition, the plethora of sourcebooks and options still makes it a complex process. You may need to check four or five hardcover books and a half-dozen on-line articles in Dragon to be sure you're seeing every choice of at-will powers for your new dwarf fighter... or you can just fire up Dungeons & Dragons Character Builder and see every official rule, for a price.
The D&D Character Builder demo covers characters of levels 1 through 3 only--enough to evaluate the full functionality of the product. It does include a small selection of races and classes from supplements beyond the Players Handbook, but by no means all of them. To get everything, including monthly updates, you need to subscribe to D&D Insider, a periodical which has varying rates. The good news is that you don't need a constant subscription to use Character Builder once it's unlocked and updated: You can spend $10 on a one-month subscription and be done with it. That said, if you're playing in an active Fourth Edition game, you may want a D&DI subscription anyway.
Character Builder has a clean interface, though one which varies a bit from typical Windows conventions. It's designed to create and edit one character at a time, and a wizard style interface takes you through each step, such as picking your race, class, feats, and powers. Once created, you can level your character up, buy it equipment, and retrain powers. All the rules are enforced, though some can be overridden. You can have higher attributes than you "should," for example; the program simply writes "HOUSERULED" on your sheet so everybody's aware of it. The best part of this is that the bulk of the math is done for you. If you equip a longsword, your "Basic Mêlée Attack" figures your total to-hit and damage modifiers, counting in every feat, class feature, and magical bonus. Swap out for that +3 Flaming Axe, and everything changes. All of your powers are printed in an array that makes it easy to cut them out and use them like cards, and they include both the default rules for the power and your personal values, calculated for your current build and equipment.
There is a downside to Character Builder. While the market of third-party Fourth Edition supplements is smaller than it was for third edition, due to a more restrictive license, there are still plenty of such products out there, and it's quite impossible to add your own classes, races, or powers to Character Builder in a useful way. You can add a "House Rule" for any element, but this amounts to nothing more than placeholder text which doesn't integrate in any way with the calculation aspect of the project. So you can create a feat which, say, gives a half-elf +2 with axes so long as they speak Dwarvish, but there's no way to only let half-elves pick it, and if your half-elf has an axe and this "feat," the +2 won't be figured in anywhere. As compared to PCGen--which is basically a script-driven engine that can handle almost anything if you're willing to deal with its complex and persnickety description language--Character Builder loses in flexibility but gains dramatically in ease of use and (if you're a DDI subscriber) completeness. Also, due to licensing changes, any third-party program which supports Fourth Edition D&D is skating on thin legal ice.
A quick warning: If someone with a full version gives a demo user a character file, the demo's response to data elements it doesn't have is highly variable. One character I tested correctly printed powers not found in the demo, but lost weapon and armor proficiencies due to the demo not correctly handling the new "Hybrid" class features. Other users have experienced different, but equally broken, results. In short, reading any but the most basic characters with the demo is probably not going to work properly.
The demo of Dungeons & Dragons Character Builder is basically just enough to show you what it can do. To get full utility, you need to subscribe to DDI, at least long enough to unlock the full range of levels and download all the latest datasets.
Note: To unlock all Character Builder's levels and receive updates, you must subscribe to D&D Insider. As of this writing, the prices vary from $10 for a one-month subscription to $6/month for a one-year subscription.