It may not drain as bad as other tablets but it is draining at a rate of roughly 5-10% per day with no use. It used to drain a maximum of 2% per day and always be ready for me when I needed it. The last few times I went to use it, it would already be drained and that is sometimes quite inconvenient. Performance has been drastically improved with this update, and using it is quite a joy, if only the battery didn’t drain when in standby like it used to.
Another issue with 8.1 is that sometimes the multitask gestures just do not work. It used to happen much more frequently before on iOS 8 but it did happen to me once on 8.1.
The issue of battery drain seems to be from Skype according to the battery usage info, but I had Skype before and never had any drain issues. Hopefully it is just a compatibility issue and will be fixed soon.