I think it's a bad trade for both teams,
Bad for OKC because they should have kept their core together and tried for a championship again. If it doesn't work, trade him next year if they can't work out an extension. I don't see how you can justify breaking up a team that just made it to the finals to get back a lesser player in K-mart and a prospect in lamb who won't be a major impact player on a team for at least a couple years, if at all.
Bad for Houston because harden will surely get a max contract from them
He worked well in OKC coming off the bench for his play making and scoring but there's no way he'll be able to lead a team as a #1 option.
Either way I love this trade because it puts the LAL even further ahead in the west