No. For the most part, they are valid complaints.
1.) Start button. Hover is absolutely horrible from a HCI perspective, most significantly being the fact that the cursor is difficult to track with your eye (cf. Most et al, 2001, and Murata, 2004.) Hot corners/edges also cause more problems on multiple-monitor systems where it's not a hot corner so much as a hotspot. Microsoft briefly experimented with this sort of thing before abandoning it years ago - hotspot common control, hover-to-select on ActiveDesktop. Microsoft abandoned it because it was horrible.
2.) Desktop is an app, conceptually. Flat-out bull****. Run Windows 8 with multiple monitors and tell me, with a straight face, that Metro is "conceptually" the OS.
3.) Not restyling Explorer, because businesses want the same desktop look-and-feel as 7. More flat-out bull****. Businesses are not going to deploy Windows 8, period. It's not going to happen. Never ever. Microsoft isn't reskinning Explorer for two reasons: businesses DGAF, and they don't want to invest in something that they are trying to EOL on the consumer side. It's not a ****ing favor.
4.) They're called App Previews because they're supposed to suck. The apps exist to show app developers two things: what the OS can give you, and how much Microsoft is dogfooding. Complete failure on both accounts. For example, the mail app doesn't save any state, so if you're typing a long e-mail, switch away and Windows 8 suspends it, your e-mail is gone. That shows Microsoft is not interested in educating their own employees about the most basic technical requirements and best practices for Metro application development. They are selling a product and their salesmen have a bad attitude.
5.) Shutting down is not difficult. I do agree with him that it's not something you should need to do very often, but their choice of placement is surprising. It is now located in a part of the operating system which was previously reserved for configuring internal, persistent state. It's counter-intuitive and shows that Microsoft does not understand their users' mental model of interacting with their computer.
Nope. It's too late for any substantial changes.