Does custom firmware affect standard features?


There is a great wealth of info on the custom abilities, how to add them and what they all do from a PC/DLNA/network point of view which I have found very useful. The one thing that is making me pause before the plunge is that I cant find any information on whether the custom firmware changes the standard features. Will all the UIs, menus, EPG layouts and controls displayed on the television and using the remote control be the same once the custom firmware is added? Or are teh replaced for something else?
I want to make sure for my partner that when she comes to use the tv and remote it all looks the same as it always has.

Can anyone put my concerns at ease please?
The custom firmware won't make the standard TV menus look any different, It adds access via a P.C. to a Web Interface SEE HERE. The Custom Firmware runs along side the standard software, It does not replace it