I've always found the opposite, in tablet mode it's extremely easy to use, much easier than an ipad. Much of that ease is because of the kickstand which allows me to use the tablet without having to hold it, or use it on my lap. I never found the weight much of an issue as I don't use my tablets with my arms up in the air, but I can see that being an issue if you, for example, use your tablet while standing up on a subway or something. Battery life does "suck", and I mean that in comparison to an ipad, BUT.... if you think about having a FULL computer in the palm of your hands then you realize that the battery life is actually pretty darn good, but of course could always be better.
Edit: On re reading your comment I see you meant the surface book and not the pro tablet, if so then I fully agree. I still left my comments up as pros to the surface pro. The only nice thing about the surface book is the larger tablet, but with less battery life and no kickstand. I'd kill to have a larger surface pro screen.