Has anyone used an SLR lens adaptor?

I own a Canon EOS T2i and my father has a large collection of Nikkor/Nikon lenses. I believe F mount, whatever the current mount is.

I would like to use them, does anyone has feedback about adaptors like this?

http://www.fotodiox.com/product_info.php?products_id=30

Or can recommend a good one?

Added (1). These are not old lenses. They are current lenses that will fit the current Nikon models.

I'm simply wondering if adaptors are a realistic solution to cross-mount compatibility. My father is quite skeptical, as he thinks it's a gimmick.

Added (2). They won't even fit on? Or they won't have all the functions.

You can only use the old lenses if they have a ring around them that moves the iris inside. You'll know it when you see it. You will need to use the camera in manual mode only. If you are afraid of manual mode this might be nerve-racking but I still suggest you do it.

Adapters are a great way to get to the heart of photography. You are in control and it only cost you $50 a lens or otherwise free. You'll get my respect, at least if not everyone's for using manual lenses. Instead of the punks who pay $2000 for a 70-200 AF-S VR III Espresso maker with AM/FM radio to take pictures of their feet.

It might be scary to be 100% in control, but if you have the old lenses you will have great glass for free.

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If they are modern they simply will not work. You are poop-out-of-luck. There's no way to move the iris. Any electronics would make it so big you'd have a focusing range of 0.3mm-0.7mm, absolutely useless.

It'll work, but only if the Nikon lenses have an aperture ring. The newest Nikon lenses don't have this ring, which means you have no away to control aperture.