Overall, I like the deal. I'm not one who buys into the conflict narrative and even if there is some sort of tension, I don't necessarily view it as a negative. If Westbrook's intensity can in any way make Durant more aggressive I think it can only be a good thing. Durant tends to be knocked off the ball and while I know he is a ridiculous shooter for his size, 5 three point attempts per game may be much (especially the late game 30-footers, it's awesome when they go in, but there isn't a worse shot in my opinion). Westbrook can be the guy to push Durant away from 3-point complacency.
Also, he's awesome at basketball. Westbrook is putting up a 20.5-5-5.5 this season while getting to the line 5.5 times per game. His TS% isn't great as he isn't a proficient 3-point shooter, but 45% from the floor is pretty good. The big knock is that he isn't a "true" point guard. Sure, he's not Rubio and will look to score, but Derrick Rose won an MVP and made a conference finals without being a true point guard. I can live with him playing outside of the normal point guard role. He's also a beastly rebounder for the guard position and is top-3 for point guards in terms of shots at the rim where he finishes 66 percent of those attempts (only Rondo is better for guys who take more than 5 shots per game).
The deal does mean the Thunder will be paying around 32 million dollars to Durant and Westbrook next season. If next year's cap is anything like this year's then that will be well over half their space. However, these two guys are clearly the two most important (James Harden being a close 3rd). Perhaps the fastidious Sam Presti will even go over the tax threshold in order to allow his team to continue to compete. Worse fates have been suffered.