For the most part, I got what I wanted out with 4e. I'm happy with 90% of the game, and think its a brilliant design and a great game. The system has a huge amount of potential, and I'm anxiously awaiting future products and ideas.
There are a few things I was disappointed in, such as roles only being combat roles, the lack of long-term injuries, non-combat powers (possibly tied to skills), and a need for more rituals. We've fixed these problems with just a few pages of houserules. However, most of 4e is pure win for me and my group- combat powers, rituals, the new take on classes (especially the warlord), consolidated skills, skill challenges, new monster design, and the core system is a thing of extreme beauty. Playing 4e for us is awesome, and running it is a dream come true for a DM.
I see 4e as very much a successor in theme and feel to BD&D, 1e, and 2e. Granted, mechanically, its quite different from any of those games, but then again, so was 3e. In contrast to 3e though, my group and I find 4e's mechanics less disruptive, player and DM friendly, and very much in keeping with what constitutes the D&D game experience.
I know I'll get some disagreement with this, but I see 3e as the abberation in the D&D family geneology. With previous versions of the game (BD&D, 1e, 2e), a player could make a character quickly, jump in, and play the game. The focus of those games was on what happened in the game, adventure, exploration, a sword & sorcery feel, and mastering play in the game. 3e had a lot of innovations for D&D, and like most folks, I gobbled it up when it came out.
But the 3e play experience always seemed hollow and inadequate to me and the groups I gamed with- there was something wrong that we couldn't quite put our collective fingers on. We had some fun with 3.x, but never as much as with 1e or 2e. Only after 3.5 came out did I realize that 3e took many of the things that made earlier editions great and overcomplicated them by codifying too many rules. I know to me and my groups, when we saw 3e's Bluff, Diplomacy, and Sense Motive skills we thought "WTF? Why do we need skills and dicerolls to roleplay???" 3e also emphasized system mastery over play mastery, and 3e was so rules-opaque and rules-interconnected, it felt like a chore to play or run the game rather than fostering a sense of excitement, mystery, and sense of adventure so prevalent in previous editions. The rules were always so prevalent in the foreground while we played that it completely destroyed our sense of immersion, or ability to identify with our characters. Many folks (myself included for a brief period) got caught up in the multiclass/PrC craze, and instead of letting a PC develop organically over time, people built their character from levels 1-20 before ever actually playing the character! While powergaming and the arms race of magic was present in previous editions, 3e brought it to new levels of escalation. Finally, 3e implicity stated that DM judgement calls and DM fiat was a bad thing, and wanted to list a rule to handle every situation, as well as fostering a sense of player entitlement. While 3e retained many of the D&D-isms of previous editions (Great Wheel cosmology, level 1-9 spells, uber-powerful casters, races, classes), it just all felt "off" in some way. I know there are quite a few folks who still love 3e, and more power to you, but the 3e play experience was deeply unsatisying for me and my groups for the reasons I gave above, and because it just wasn't D&D to us.
For me and my groups, 4e has remedied the situations in 3e that made it an unsatisfying play experience, and brought the game back closer to its roots, while at the same time revolutionizing the game and injecting some much-needed new life into it. Gone are the many of the tired old D&D-isms that didn't really add anything to the game, and some incredible new ideas have been introduced to really get my creativity going. D&D 4e brought back the sword & sorcery feel, the mystery, adventure, and sense of looming danger me and my groups enjoy so much. I for one am very happy 4e was not a continuation of 3e- IMO the 3e line has run just about as far as it can possibly go before eventually crushing itself into extinction under its own weight and system design.