I use my Surface strictly in landscape orientation, and use Online Textbooks, eTextbooks, textbook eBooks, exam copies | CourseSmart
for 3 of my 6 textbooks (only three I needed were available as an eTextbook, but I have the option to add 3 more to my account for the semester). Coursesmart is run directly from their servers and since I'm on campus for my classes, I am always connected to my school's wifi. The default view mode for the textbooks is annoying, and in that matter, I would agree with you about the aspect ratio. However, change a few settings on CourseSmart's interface
and it eliminates most, if not all issues. I can access my books offline if I act with the premonition that I might not have wifi; I can also print off entire textbooks, as well as share individual pages with professors/classmates via email or other social networks. Keeping in mind that CourseSmart does not
have an app in the WStore (and does have an app for iOS/Android), it has, and still is, taking some time to adjust to the interface they use - once you are acclimated, though, it's just as simple and effective as a traditional textbook (navigating pages, highlighting text, adding notes via text or stylus to specific pages, bookmarks, etc.) - I just save money, weight, and time with this method.
You can buy or rent books individually, or purchase a subscription - I chose the latter. The subscription is $200 and allows you to add up to 6 textbooks to your bookshelf for 150 days (slightly longer than 1 semester). If I had rented my eTextbooks, I would have spent $225 for the three I have - if I had purchased traditional textbook renditions, I would have paid $476.89 - and that's excluding the materials for my other courses.
Long story short, I have not experienced any problems using my Surface for eTextbooks. In fact, many classmates have been impressed at both my Surface and the utilization of eTextbooks. If you are mentally aware of what's going on, staying ahead of classmates, and on par with the professor, is a breeze. My CompLit II professor was also impressed to hear my answer of 8.1 when asked what OS I was using on my devices.
I will have to play it by ear, as it is early in the semester, but initial experiences are very positive.