it looks terrible, doesn't have apps, compatibility (fixable), other company support, dev loving.
I get that some beancounter is probably saying "hey, we pay Google 5 bucks per phone, if we didn't have to pay that, we'd make more profit", but breaking everything isn't the solution.
And how they ignore their users for years over touchwiz, I'm not too trusting that Tizen will give users what they want.
It /can/ be fixed a bit, by making a Cyanogenmod like version of it, release the base code somewhere, like ASOP for Android, and it would get some love from the dev community I'm sure. But will/can samsung set it free? From past experience they want everything kept very close.