Joy... "Twitter is deeply integrated into Mountain Lion". I don't use FaceBook and I don't use Twitter because I don't want to. Granted, I still won't "have" to use Twitter, but I'm going to be forced to see it all over. If I want any third party integration, that should be my choice.
Granted... this is a very early build and things can change. I would expect the features they're including in this build will, however, end up in the final build. Especially given all the changes that were forced on us with Lion, I don't see any reason for them to change direction now.
GateKeeper... although not really an issue as it is now, I can already see the day when we'll need to jailbrake our Macs to install non-authorized applications.
I think the integration and similarity to iOS apps will be a good thing.
The vast majority of users out there will agree with you. Us old timers haven't really been happy with the direction things have been going since Lion. Most people will love it though. We'll all be using iPads with keyboards in a few years. Apple's financials speak for themselves. What they're doing works. Regardless of how vocal the minority may be, it doesn't make business sense to cater to them (us).