I will defend the new system, as best I can with the limited amount of information provided so far...
It really comes down to opening up the alignment system to accomodate for a broader view and a much wider range of definitions. The old school 9's compacted your basic moral/ethical codes of conduct into slots. If you were CG you did this, and if you were LE you acted like that....and so on and so forth. All very aptly described in this and other posts, as well as being basically defined in the handbooks of old.
Surely you could go outside of the norm, thats what roleplay is all about, but the definitions for each subset of the 9's meant that a DM had to decide what repercusions could/should/or would happen when a player went outside of his/her alignment. The most significant being the three big alignement classes (Paladin, Druid, Ranger...barring any aberations like the anti/dark Paladin etc...). The real hard part is defning where those lines are drawn, and if Player and DM didnt see the line drawn in the sand the same way...here come the arguments...hehehe. You can see the gaming parallels being drawn here in this post.
The 9's of old had gaming impacts that could be huge, especially for the three "Oh crap you just busted that alignment and now your gonna pay!" ones. Aligment also had a sizeable impact on other aspects of the game as well, the "Detect" system being a good example.
Most of the time these issues get settled during a gaming session. But I bet there are a good number of people out there reading and posting who have played in some sessions where pizza got tossed, beer got spilled, and "You wouldn't know the definition of LE if Artemis Entreri stabbed you in the face!!" type insults were shouted across the table.
4E puts alignment squarely in the "personality" corner...for lack of a better term. Its a part of the general characteristics of a player, NPC, or moster. Not the defining conduct measuring stick. What that does is open up the wiggle room on what a character is allowed to do or how a DM measures the damage done when a player goes outside of the norm.
What we now have is the basic good vs evil axis...with both extremes LG (for example using a leader role...ranging from an elected benevolent president to overzealous religous tyrant) and Chaotic Evil (ranging from your military backed cutthroat dictator to murderous lunatic of a monarch by birth). Everyone else is in the middle.
LN is covered in the middle (your average citizen who follows the laws of the land, but is not neccessarily good or evil...ie he/she has viewpoints that may go either way like legal prostitution or indentured servitude, maybe bribery under or over the table is a normal means of commerce, or class systems by birth are seen as normal and "ok"). CN is likewise covered in the middle (your average street urchin/thief doing whatever it takes to survive by whatever means but is not neccessarily a good or evil person but rather commits both types of acts whenever he/she feels like it).
In 4E it seems only the extremes of the axis are noted, and even then the game effects are likely to be minimal. Whats important is the roleplay and judgements of the players (possibly with a lot more emphasis on insight/perception).
To me, this opens up a whole line of possibilities, especially with regards to classes who were formerly tied to alignment as a "ball and chain" type of requirement that now doesnt have to be house ruled to death.
That is at least what I am getting out of the information so far.
Sorry for the length and our wait will soon be over
Mal