It looks like the designers of this version are trying very hard to bring computer gamers into the realms of paper and pencil gamers. This is most clear in the character creation and the related sections of the Player's Handbook. Every character class is given a bunch of special powers to choose from. Some of these are available in any combat, and some are limited to once an encounter or once a day. All of them (that I've seen at least) are combat related.
They seem to be pushing back to the combat emphasis of the early RPGs. While there are still skills for non-combat times -- and any RPG devotes a good amount of the basic material to combat by necessity -- they seem to be downplayed. Further, there is the discussion in the character creation area, which is reflected in the information given when I signed up for the gaming slot at ConDor, for putting characters into 4 broad archetypes: "Controller, Defender, Leader and Striker," all of which are defined in terms of their use in combat.
Further, all of the classes are described in terms of their combat roles. For example, the ranger -- which was a fighter sub-class in 1st edition and maybe 2nd edition -- was always treated as more of a man of the woods. Someone skilled in fighting, but also in a lot of other woodcraft skills -- not unlike Aragon whom I am sure was at least unofficially the inspiration of the ranger class -- and it was these other traits that defined the ranger. Now the ranger is just a specialist fighter with specific combat abilities. Little is even said in the overview about their woodcraft skills.
One of my favorite aspects of 1st and 2nd edition AD&D was the ability to create multi-classed characters. At least in the groups I played in, this was a pretty flexible option for non-human characters. I've played many Fighter/Magic User/Thieves at times, and I think I even had a gnomish Magic User/Cleric once. In third edition (or at least the 3.5 rules I've got) this was taken away but the ability to choose a new class at each level -- an option for humans in 1st and 2nd edition with a few more restrictions -- gave a similar option for higher level characters, but still left 1st level magic users a bit vulnerable. As near as I can tell within the official rules this is NOT an option in 4th edition. Once your character starts as one class, you are stuck with it. Of course this means that the classic D&D, or at least Basic D&D, elf as a fighter/magic user isn't available! There are multiple paths at higher levels for most of the classes
One thing I haven't looked into too much in the books, but played with a bit in the character generator, is the creation of magic users. However, from what I saw there it looks like they have replaced the classic D&D spell system with a video game power system. Many of the classic spells are available, but they seem to work more like powers then spells of old. If I'm right, this is a major change in the mechanics of magic. I'm sure that it is balanced and works, but would be a real change for old players (like me) who often have used spell-users (unlike me).
After next Friday's gaming session, I'll have a better idea of how I feel. But I suspect that if I get back to playing as the ref or game organizer and choose to use D&D as the basis, it will be one of the earlier editions, not 4th edition.