ET News is reporting that starting with the Galaxy S5 next year, Samsung may be begin replacing the plastic we've been seeing so far in their phones, with aluminum, magnesium and other metals in their smartphones' bodies, as part of an overhaul of Samsung's design language, which I also think is direly needed.
After much criticism over the Galaxy S3, for its weak design and non-premium looks and feel, and then new criticism compounded again with the Galaxy S4, which was merely an iteration of the same thing (on the outside), Samsung finally seems to have agreed that maybe they shouldn't use the cheapest possible material to create their $650+ flagship devices. For an extra few bucks per device, they can make those same phones feel and look far better, and make them out of aluminum, and according to these rumors, magnesium, too.
They will apparently start with the Galaxy S5, and then use the same type of body and design for other devices, too (Galaxy tablets, Note 4, etc), including lower-end ones as times moves on, and the economies of scale allow them to do that for cheaper devices. This part isn't much of a surprise, since that's what Samsung has been doing since the Galaxy S3, too – making all the other devices in the image of their flagship.
I don't believe metal is the ideal material for a smartphone or a tablet, especially since it presents a pretty big weakness for radios, and the manufacturers need to design around that, which if not done right, could make the devices uglier with the plastic parts they may need to put in there. But overall, it's probably the best we have right now if we want our devices to look and feel really high-quality.
At the same time, I'm hoping Samsung and others are also researching new types of materials to use in future phones that can offer similar premium feeling, but are much better for the radios, and therefore can also be used to create unibodies easily (unibody phones are usually the ones that have the best design and premium feeling).
Either way, if you want a metal device from Samsung, you might want to hold off buying one this year from them, and wait at least until the Galaxy S5 shows up sometime next May.