Finally got it long enough to justify a cut tag.
Something I forgot to mention: Classes, and with greater variety monsters, have all been assigned a specific 'role'. For PCs, these roles are: Striker- single target damage; Controller- AoE; Defender- tank; Leader- heals and support. Monster roles are a little different, much more widely varied, and based mostly on their function in combat. Examples include: artillery, minion, brute, skirmisher, elite, etc. These roles are designed to just make matching up a group easier. One character from each role will make a sufficient group to deal with most challenges.
Warlord is a new class designed to fill the same group role that a cleric would, but based on physical combat instead of divine power. Like the upgraded cleric, many of the warlord abilities offer combat and tactical support (attack and damage bonuses, shifting, or healing) to allies in addition to modest damage. A solid class by itself, and possibly succeeds where the old paladin failed: as a viable substitute for a cleric.
Wizard. Let us begin by admitting that wizards in 3.0 were crap before about 5th level, and after that began a rapid rise through good and right on into ridiculously overpowered. They have been given their rightful nerfing, back into line with other classes. That having been said, it's still a powerful class. Many of the old spells you may remember still exist, and often in a buffed form. And with the encounter powers available, wizard longevity over the course of the ingame day has been increased dramatically.
'Epic destinies' are very unrestricted prestiges that confer few but very powerful abilities in the 21-30 range. They also contain an entry describing your characters exit from the mortal realm at the completion of the destiny. Obviously, you can do whatever you like with that, and I suspect most people will ignore that paragraph entirely.
Skills have been simplified and consolidated into a much smaller list than in 3e. Training a skill has been changed to a one-time investment which grants a constant +5 bonus, rather than a per-level allocation of skill points. To compensate for the sudden drop in skill modifiers, half your level is added to any skill check. This makes the final formula (d20 + 1/2 level + ability modifier + 5 if trained + misc). Cross-class skills are no longer permitted, but since very few skills can't be used untrained, this doesn't much matter.
Feats have been divided in much the same way the level range has been. 1-10, 11-20, and 21-30. You may take feats from whichever group your character fits into, or lower. The feats give mostly the same kinds of bonuses as before (new proficiencies, skill bonuses, X more uses of Y class feature), but you get feats more often. Every even level, and at the start of a new tier. ex: 1,2,4,6,8,10,11,12,14...
Equipment next.