While I hated to see Mike's character go, I don't agree with anyone completely taking his side... he blamed Walter for the whole (previous) operation's problems, but it was far from that simple.
Walt had to protect Jesse from Gus (and the DEA) early on. I'd have to re-watch to remember the exact details, but Walt did what he did to try to keep Jesse, Hank, and himself alive. Yes, his ego was always a factor, but there was more to it than that... and Gus had an ego himself. I recall him saying something to the effect of, "the cook continues". He didn't want to stop producing despite pressure from the DEA and cartel.
Had Walt not acted the way he did, Hank and/or Jesse would definitely be dead, and there's a good chance (IMO) the DEA or the cartel would have busted Gus's operation anyway.
Of course, the big link (for Hank) was the restaurant bag in Gale's apartment, so maybe things would have been fine for the operation if Jesse (under Walt's influence) hadn't killed Gale. Then again, they wouldn't have had to kill Gale if there wasn't a threat to Jesse and/or Hank and/or Walt, so...
...like I said, it's not as simple as Mike implied... Walt didn't just F it all up. And he really doesn't get enough credit for supplying the market with the purest/most potent meth around. Evil or not, part of me is still rooting for Walt.