I own a bike with an IGH.

I do find that removing the IGH back wheel is a lot more difficult than with my derailler bikes. However...um...let me put it this way. If I practiced every day at it, it would be a little more work (and as other people said don't forget that you need the wrenches) but not a huge deal.

The real problem is simply that I forget the steps I need to go through to do it, so when I go to do it again I can't remember how I did it last time. Whereas I've taken the back wheel on and off enough regular bikes enough times that I know how to do it. Well...lol...sometimes I still have some issues with getting the wheel back on in the right place with the chain.

Those are my thoughts at least...note that this does not stop me from using an IGH on my winter bike though.

Civia Cycles also has videos on how to do it so you can see for yourself -

This one -
http://civiacycles.com/civiaMedia/Al...bleRemoval.swf

Then also this one -
http://civiacycles.com/civiaMedia/Al...eelRemoval.swf

To remove the rear wheel. To put it back on again, it's this one -
http://civiacycles.com/civiaMedia/Al...bleInstall.swf

Then this one -
http://civiacycles.com/civiaMedia/Al...eelInstall.swf

For whatever reason I always find taking the shift cable on and off to be a lot more annoying than it looks like in the video...kind of like how with a derailler putting the rear wheel back on in a video often looks easy but in reality I always end up screwing around with it trying to get the wheel back in the chain in the right position, lol.