Paper by Studio Fifty Three (iTunes link), which is admittedly a rather un-Googleable name for an app, is the ultimate in distraction-free simplified idea sketching. Your options are ridiculously limited - but that's part of the beauty.

The brushes, available via in-app purchases with only the basic fountain pen free, feel wonderful. It's a pleasure to use, sketch out ideas and brainstorm - just don't expect a full-on drawing application.

Interface

Upon launch, Paper presents you with a skeuomorphic selection of sketchbooks to separate your ideas. The covers can be fully customised with colours or photos, and you can create or delete sketchbooks with ease.

Upon opening a sketchbook, you can flip through pages or use the same 3 interface buttons to add, delete or share your sketch.

Touch the sketch to open it, and pinch to close. These interaction come naturally to anyone familiar with an iPad. To open the tools drawer, pull up from the bottom of the screen. Pulling on the left or right side flips pages over, as you'd expect.

Click a brush, click a colour, push down to draw and be creative.

One final incredible feature that I love is the rewind function - hold two finger and rotate anti-clockwise to undo brush strokes from the current session.

The Brushes

Fountain Pen - free, not mixable. Slower speed results in thinner lines.

Pencil - $1.99, mixable. Very thin, feint lines then blend to create darker colours.

Highlighter - $1.99, mixable. Medium thickness, draws on top of other brushes and blends.

Technical Pen - $1.99, not mixable. A very thin technical drawing pen that accurately produces small 'sploges' of ink at both ends of the line. Slower brush speed results in thicker lines.

Watercolor brush - $1.99, mixable. Very large, light flow of blendable paint. Slower strokes produce greater density of ink.

When you click the brushes for the first time to purchase, you'll be presented with a small practice area - just another feature that really makes this app stand out.

Comparing Paper to Sketchbook Pro

Once all the in-app additional brushes have been purchased, Paper will have cost $8, so I think it's fair to ask how this app compares to it's closest competition - Sketchbook Pro for $4.99. But the truth is that they couldn't be further from each other. Sketchbook Pro is a professional art and painting application: it has a multitude of options, brushes, thickness and flow adjustments; full color mixing and zoom functionality for the finer details. It's also clunky and unresponsive though, even on my 3rd generation iPad. For some, it's a gateway to digital creativity. To me, it's overkill.

That's where Paper fills the void. Paper has stripped functionality down to the bare essentials, creating an incredibly responsive interface in the process while maintaining the feel of beautiful brush strokes.

For similar apps, check out these 3 doodling apps or the limited Sketchbook Express.

Limitations

The color palette which consists of only 9 colours in total is the most disappointing thing about Paper, but feedback in the community support site is mixed - some love the fact that it has so few colours that work well together and don't want it to become just another painting app -  while others have posted wonderful ideas on how to integrate a full or at least expanded palette without compromising the simplicity. It's great to see the developers on hand and responding to the ideas though, either way.

The other most common complaints are of fixed brush size, and pricing. While I can't say I'm bothered by brush size that much, pricing is certainly a concern - it is expensive compared to similar apps. However, I believe this premium pricing will ensure the app remains updated over time, and frankly I think it's worth it.

Note that the limited feature set also means the app runs responsively on 1st and 2nd generation iPads too, though only the 3rd gen supports the retina graphic detail.

That's not to say you can't create incredible artwork in the right hands though - this is an illustration using Paper by Sam Spratt which I believe you'll agree is quite incredible.

Verdict

Despite the high price, Paper is my new sketching app of choice for any random ideas where I would otherwise have used an actual sketchpad. In the real world, I don't have an infinite pallette of pencils, paints and varying width brushes - and it's that realism that makes Paper so comfortable for me. I do own Sketchbook Pro, but I can't figure out the interface and end up being frustrated by the unresponsive brush strokes.

As Barry Schwartz explained - more choice often equates to less happiness. It's this principle of less equals more that has made feature-limited iPad devices the most successful, and Paper epitomises that in a sketching app. Whether you agree or not, you can still try Paper for free and have full use of the delightful fountain pen brush, so what's stopping you?

Let us know what you think in the comments, and be sure to check out the newly updated Best of iPad Apps page.