Is 4e a complete game in that I can sit down with a PHB, DMG, and MM and run a game? Yep, and a damn good game too. All the tools you need to run a 4e game are already there. Thats not even up for debate, its a simple fact.
Is 4e complete in that there are some concepts, races, classes, powers, rituals, feats, etc that still need fleshing out, and that I'd like to see? In that case, then no, 4e isn't complete. However, when people start wailing that 4e isn't "complete" due to X being left out, that is a highly subjective thing. For example, some folks will complain 4e isn't complete until the barbarian, bard, druid, or munchkin nosepicker class is official. Can the game be run without those classes and still work fine? Yep. Or maybe another person could care less about the PHB2 classes, and be more about ranting that 4e isn't "complete" until psionics are back, or whatever their pet cause is. Each person will prioritize certain things above others due to their opinions and tastes, and as such, saying a game is incomplete because I can't play a fiendish gelatinous cube ranger/psionicist/ninja is being rather ridiculous. Since this aspect of "complete" is completely subjective and based on individual tastes, there cannot be an objective answer for completenes based on this kind of criteria.
Wizards has already said they are slowing down the release schedule in order to get things right the first time, and to prevent munchwankery crapfests like 3e's Sword & Fist, Tome & Blood, or Defenders of the Faith, (and the later Complete X books to a lesser degree) for example. And if Martial Power is any sign, this approach is a great idea- Martial Power is a SOLID book, and much better designed than almost anything during the 3e era. If the price for this kind of quality and inclusion of some missing concepts is a little waiting, I'm all for it.