I've only been in the UK, where I live now, but the Ikea stores here are laid out in such a way that you can't just walk in and go straight to the department you want. Instead you end up having to go through the entire store and the check-outs are at the end. This is one of the reasons it's such a mob scene in there, because you've got vast hordes of people just trying to get through the place to pay.
A Swedish friend of mine told me that when Ikea originally started up in Sweden, it was done that way deliberately as a way of making sure the customers were pretty much forced to see everything Ikea had to sell, whether they wanted to or not. Also, putting in a restaurant and kids' play area meant that many people saw a trip to Ikea as more than just a shopping trip, but also a day out. It was a highly innovative idea in Sweden. The big one-stop place was a concept that was readily embraced.
The thing is, there aren't that many people in Sweden, particularly for the size of the country, so Ikea shoppers there don't face the same crowd congestion that stores in more highly populated countries do. UK Ikea stores are always packed with people. I know that my husband feels like he's being sucked into hell when we go there because of the impossibility of just buying what we want quickly and then getting out (last time we went it was for some curtain rods and a couple of desk chairs and it took 3 hours from going in to getting out, and that was with us already knowing exactly which items we wanted before we went in!).
I like Ikea products though. Good value for the money, at least over here, and I'm assuming Ikea is the same in every country. If they ever start doing catalog sales, I'll buy a lot more often from them.
Good luck with the experience, but plan on being there for a while.