Although Wacom says that the Bamboo Stylus is "for iPad", it'll function with any capacitive screen device. There are no fancy inner workings here to make it function particularly well with the iPad in particular - just the little capacitive bubble on the end.
However, the touchscreen sensitivity of iOS devices, including the iPod Touch and iPhone series, makes an excellent pairing with this tip. Using other, less sensitive, devices like the HTC Legend we found that the screen would occasionally miss lighter prods. Some degree of force is still required with an iPad, but it's consistent. Just grazing the Bamboo stylus along the surface won't register - apply the tiniest bit of effort and it will though.
The tip of the pen is firmer than the skin of the average fingertip, so with a light touch the contact surface area is very small. As the tip is a hollow, balloon-like semi-circle, you might expect accuracy to be compromised by the squidgy tip, but it's remarkably reliable.
The iPad's capacitive screen registers the centre of the surface area of the tip as the point of contact, so while there's some give in the way the stylus interfaces with the screen, it always feels reliably pen-like. There's no magic going on behind the scenes though - this stylus won't turn your iPad into an Intuos4. The stylus houses no circuitry, magnets or electronic bits. It's basically a stylish home for the nib to perch on top of. Indeed, despite the nib flexing to form a larger or smaller surface area the harder you press, this doesn't result in a change in the thickness of line produced - it just feels nice.
This is reflected in the very reasonable price tag though. The Bamboo stylus is an accessory that alters your experience of touchscreen operation, rather than adding features or fundamentally changing the way it actually works.
It's particularly useful for writing words rather than painting - which works surprisingly well with a finger alone. Wacom seems to think so too, judging by its dedicated Bamboo Paper iPad app. This notepad app lets you scribble away on virtual lined paper, and uses some clever software trickery to alter the behaviour of the pen's output depending on how fast you scrawl away. Like the pen itself, it's designed to make writing feel natural and "real".
As pleasant as it is to use, you should still ask yourself whether the Bamboo will fit into your everyday iPad usage - bearing in mind that there's no elegant way to keep the two together. If you just want to dip your toe into the world of the capacitive stylus, the Griffin alternative sells for as little as £8.99, but the build quality brilliance of the Wacom makes this worth the extra cash if you're sure it won't end up gathering dust within a week.
The Bamboo Stylus supplies an impression of increased accuracy and fidelity rather than the real thing, but when the experience of using it is so positive - and the price so reasonable - we don't really care. As the iPad's capacitive screen is already so finger-friendly, the audience for this stylus is likely too limited, but it makes freehand writing feel far more natural than with a finger.