@Brooks Barnard @CallChrisNow "Use Android apps", yes. But have access to the Play Store to download those apps? Heck, no. So as @CallChrisNow said, anyone with money vested in apps purchased through the Play Store will be SOL using a Tizen device. Can you say, "return/exchange"?
Samsung already has their own mobile OS which they sat on and didn't do anything with: Bada. They may try to make a go with Tizen, but the reality is "no apps, no critical mass". Unless they can get developers on board, a new mobile OS is a waste of time. In the meantime, they will be ceding ground to LG, HTC, Moto and other device makers willing to pick up the Android slack. Android is free. If they want to create an ecosystem, they can do it around Android at the same cost or less than if they did it with their own mobile OS.