To me it rarely feels inconsistent. I like that the back button remembers the context for whatever my current action is. It means I don't have to keep it in working memory. I just press back when I'm done.

I also disagree with Gruber's complaint:

Here’s one thing I don’t like about the Android Back button that I’ve never seen a counterargument for: it presumes that you, the user, remember the activity stack. If you turn your phone on and you’re looking at a web page in the browser, if you don’t remember what you were doing immediately before opening the web page you’re looking at, you have no idea where you’re going to go if you hit the Back button. Could be another app, could be another web page, could be the home screen. And if hitting the Back button takes you somewhere you didn’t want to go, there’s no Forward button to reverse it. It’s like leaving a breadcrumb trail in the dark — you have to remember where the breadcrumbs are because you can’t see them.

http://daringfireball.net/linked/2011/11/02/defending-androi...

Actually, I think what's nice about it is that you don't have to remember the activity stack. You just hit back if you want to go to the previous activity, and if you don't want to go to the previous activity, you go to the home screen. Why would you hit back if you didn't want to go to the previous activity and also didn't remember what the previous activity was?

Here's a common analogous scenario for me. I unlock my phone to a web page. I finish reading the web page and then go, "How did I get here?" I hit back, which usually takes me to the previous web page, to google reader, or to twitter. I then go on with what I was doing, probably skimming feeds. It's a great, natural workflow that allows me to pick up exactly where I left off.

I wonder how Gruber manages to use web browsers' back buttons without getting confused. I mean, when you hit it, it can go to SOME RANDOM WEB PAGE!

As for the forward button, it's just a matter of hitting the exact same link or button that you did the first time. Forward is redundant.

And of course, if you're ever confused, you can just hit the home button and start over. This is your only option in iOS. If you get routed to twitter from another app, and then you want to go back? Hope you remember what you were doing before. In fact, you'd better make sure you remember if you want to get back. Because you're going to have to go back through the home screen to get there.

In my scenario above, ported to iOS, if I wake up my phone to a web page, I basically have no way to go back to the activity I was doing before the web page except to just remember. That, to me, is a much worse workflow. There just aren't any breadcrumbs at all.

I also don't think there's any way to get rid of the OS-wide buttons, because there are basically two axes of navigation. There's the OS wide one along which the back button acts, and there's also the in-app one that takes you between panes of an app. Swipes already move you between panes. How can they also move you back in the activity stack?

I do agree with you that icons are outdated. I hope Android steals more from Windows Phone 7. Those tile are gorgeous.