I'm a huge fan of this mode. I can zip through my inbox, the tabbed browsing is great and I love the expanded keyboard with punctuation available at a press instead of buried in another menu.
About the only time I turn my 6+ sideways is for images taken in landscape or when on the internet reading an article. The portrait mode keyboard. Is as about as good as it gets for me.
I use landscape for watching videos. That's it.
It is no easier to type and I dislike the reduced up/down screen real estate when using landscape mode. The screen is 50% filled with the keyboard as opposed to 33% whilst using portrait.