Retailing at £14.99, it's not the most expensive extra we've seen appear for a console, but the fact that high profile titles are adopting it as an optional control method - such as Resident Evil: Revelations released today and the upcoming Kid Icarus - does that make it an essential buy?
The Pad is more shell in shape and form: its a dock frame in which to lock your 3DS into. In doing so your right hand now grips the right side of the Pad Pro, where on there's an extra analog stick, mirroring the one on the left of the 3DS console.
The console, in this way, systems can have two analog inputs, plus two new buttons - two triggers, sitting underneath the standard shoulder buttons.
That's it? Well, yes. Yet, if this innovation is increasingly adopted by developers is likely to fundamentally change the gameplay in video games for Nintendo 3DS.
As mentioned, currently the only game that uses the Resident Evil: Revelations, and as we mentioned in our review, you can happily do without it. But how does the optional accessory feel - and is it worth the buy?
Weight and Ergonomics
Surprisingly, the Circle Pad Pro is quite heavy. This is clearly not a empty plastic shell: the body is strong and likely impact resistant. It weighs in at around 150 grams - remarkable considering the weight of the console if only 75 grams more.
The design could well put an end to hilt cramps caused by prolonged play on the 3DS. The pad on the right is built slightly deeper into the casing than the unit's own. And its casing isn't wide enough to make reaching over to hit the face buttons an issue. The case's build is such that the 3DS R button is covered, but the Pro compensates with its own.
The console fits snuggly into the shell's interior by way of six rubber buffers, avoiding any shake. As usual with Nintendo's staunch stance on safety, the package includes a wrist strap and strict instructions to attach it to the 3DS and always wear when playing.
Once the two are combined, there's space on the back to connect the power supply - you're going to have to wave the 3DS dock that came with the unit goodbye - and a large space on the front for connecting a headset.
The weight of 150 grams reflects the fact that the Pro needs powered by a AAA battery. A flap on the front of the Pad (under where the 3DS unit sits). So early on into testing we can't confirm the battery life, but the Japanese firm has confirmed an estimated 480 hours of play. Not bad.
The Circle Pad Pro communicates with the console via an infrared system, with the Pro's back hatch placing directly over the receiver / transmitter that's on the back of every Nintendo 3DS.
In addition to the circular pad on the right, the product includes a replica R button, which is otherwise inaccessible on the 3DS. The real news, rather, is the addition of two new buttons, ZL and ZR, which are very similar to the two triggers on the Classic Controller Pro for Nintendo Wii.
Will this accessory will become an indispensable tool for owners of Nintendo 3DS? It's hard to say at the moment. But if Nintendo follow past example and release an updated version of the console somewhere down the line, it's easy to imagine the second stick will be in-built into the unit.
And it's something it's not going to spring all of a sudden: it'll make sure that will be communicated to developers as soon as possible. If we see the adoption of the "Circle Pad Pro Compatible" option wholesale in the near future - then it's a certainty of what's to come.
It's not the first time Nintendo have adopted new technology during a console's lifecycle: the Wii's Motion Plus saw a slow start in introduction, but its now built into every remote. The same could happen with Nintendo 3DS.
Needless to say that build, whatever it may be, will be less bulky, cumbersome and ugly than the current Circle Pad Pro; differences that will make the accessory, as it is now and with a low support count of titles, as a non-essential extra.