But making it out of plastic would lose some of the thinness/strength benefits from a unibody aluminum enclosure.

Apple uses a single block of aluminum: http://thetechblock.com/wp-content/uploads/2012/08/iphone5_t...

Could be. The Nokias I mentioned use one block of plastic (or polycarbonate as they call it), but they are indeed thicker.

As an anecdote my laptop (MBA) and phone (N8) have a full aluminum body. I prefer the high quality plastic of the Thinkpad & N9 though, it's "friendlier" to the touch than the cold slippery metal.

> Actually Apple are pretty bad at picking phone materials period.

Which is funny, because they filed a patent[1] over two years ago for a process to make scratch-resistant stainless steel.

[1] http://www.geek.com/articles/apple/apple-to-patent-process-f...

Stainless steel is a pretty interesting material, but probably not a good choice for this design. A new variant of stainless probably makes it an even poorer choice (because full characterization is a prerequisite):

- Some variants of stainless steel are ferromagnetic, which would mess with the compass.

- Steel has very poor RF transparency, which would impact performance even with glass windows.

- Steel is heavy.

- Steel is far more difficult to machine: with Al you can easily (quickly, with little resistance) mill the curves and cavities that Apple likes for unibody design. Meanwhile steel chips, heats, and provides much resistance to a mill. It requires more finishing and incurs more tool wear.

I agree there are drawbacks to stainless and that it would be difficult to design a cellphone or other RF device entirely or predominantly from it. However, the patent does show that they have gone so far as to research and patent a process for improving a material for use in their portable devices. This makes the apparent lack of care in choosing the anodized aluminum for the iPhone 5 surprising and disappointing.

> Glass is probably the poorest material possible for the obvious reason.

Yet the iPhone 4 that I own since about release day has fallen an impossible number of times from unsuspected heights, and both front and back panels survived the abuse. I'd buy another such "poor material" phone anytime.

The only shattered iPhone 4 panel I encountered was my boss's, and it fell from the kinetic equivalent of second floor onto concrete. He's still using it because only a corner is affected, and a replacement front panel costs too much (I bet he'll get an iP5)

Ok, but what does that prove really? The bottom line is that while virtually all phones can crack their screen, i4(s) is the only phone that can just as easily crack its back.

The most important property of glass is transparency, while the big disadvantage is that it breaks catastrophically. You get no benefits and all of the downsides when using it for the opaque back plate. It does look nice, but there are other nice looking materials available.

And George Burns smoked several cigars every day for 70 years and never got lung or mouth cancer. Many, many, many other people were not so lucky.

Anecdote: My 4s fell from pocket height onto concrete. Screen was shattered, but the phone was still usable.

And, for "just" $200, Apple replaced it with a new one.

A small-ish point:

While the glass Apple chose does have issues with very hard impacts (the stuff that lead to catastrophic failure), it has really impressive resilience to minor wear and tear. It's difficult to scratch with metals and doesn't chip or dent. Yes, sand/silicates will scratch it, but not softer materials.

Further, ceramics and glass have excellent RF transparency, especially relative to metals. As you can imagine, this is incredibly important in smartphones. This has been a pretty big design challenge for Apple in the past: the Titanium Powerbooks has horrendous wireless performance, and generations of iPads and iPod touches have had to have glass or plastic windows in their backs. The iPhone 5 has two glass windows in the back for this reason. Note that stainless steel has poorer transparency than Al, and some types are ferromagnetic.

I definitely like the polycarb that Nokia is using in the Lumia line. That said, the feel that Apple has created by its material choices in the iPhone line is very nice, and that this complaint over scuffing is minor. Wear and tear happens, whether to plastic or steel.

This seem pretty subjective ... I love the various aluminum ipod-mini/nano models, for instance. In my experience, they're almost perfect.

Apple's mistake with the earlier metal ipod seems to have been not that it's made of metal, but that it's made of highly polished metal (which will of course be subject to scratching, fingerprints, is more slippery, etc).

"High-quality plastic" can easily suffer from the same issues if it's glossy; I own phone made from very glossy plastic, and while it's beautiful and extremely well made, it's also very slippery and very prone to picking up fingerprints.

So using a metal back with a less finicky finish, as they did with the iphone 5, seems a pretty reasonable move.

Nitpick: There are tons of high-durability glasses that you'd have to try pretty hard to chip or break.