I would like to know the opinion of some users using (or not) the hidden volume encryption feature of Truecrypt. Personally until now I never used this feature: on Windows I encrypt the system drive as a standard volume, on GNU/Linux I encrypt using LUKS which is Truecrypt's equivalent to standard volume. As for data I use the standard volume approach as well.
I read that this feature is nice and all, but it isn't really used by most people. Do you use it or not? Why? Do you only store inside it VERY sensible data or what else? Because technically speaking doing a hidden volume which has (almost) the same size as the outer one doesn't make sense: the outer volume will be encrypted but no data will be on it, which will appear very strange.
So not only one has to plan which data store where, but has even to remember each time to mount the outer volume with hidden volume protection (otherwise there'll be a data loss when writing to it). It's a bit messy: hidden OS + outer OS + outer volume + hidden volume = 4 partitions :(
Similar question about the hidden operating system (which I don't use [yet]).