Like the majority of tablets on the market, the battery is sealed inside the unit. The only manufacturer who have not done so is Toshiba on their new tablet but not had much interest in their design and performance in the past so not on the books for me. Generally, the battery life cycle on these devices (in general) are far beyond better than what we were used to.
I mean I purchased the iPad (original) the day it was out and still had no issues with battery performance. I still get the 8-9 hours that I originally got. If it does get to the stage where a battery needs replacing, companies do offer a service to do so which was not as expensive as you think.
I had a Sony Walkman which cost me quite a bit in the day and 3 years later when battery life decreased, I went through the battery replacement service which only cost me around £40. Not saying that how much the Tablet S battery will be to replace but I am sure measures will be put in place for that.
If that is a concern for you, maybe you should consider the P which has a user replacable battery but bearing in mind, buying additional batteries also has a cost so in reality, the only difference in the long run is one you have to send away but both could cost around the same for a replacement battery.
From past experience, I wouldnt put it down to a bad product or bad design. Just something that you have to remember to do further down the line regardless of the product.
