One of the benefits of Google's approach to Android is that there are many OEMs designing interesting hardware. Users get their choice of form factors and specifications. One choice users are faced with currently, and in the future, is if they should upgrade to a dual-core phone. There are only a few mainstream devices on the market with dual-core chips, including the Motorola Atrix and Samsung Galaxy SII.
There are definitely some advantages to having a dual-core device in your pocket, but the benefits might not extend as far as you'd like. Some single-core phones could even offer a similar experience while avoiding some dual-core issues.
System support and speed
As of now, the only version of Android that truly supports dual-core systems on a chip (SoC), is Honeycomb. That means that even phones running the newest version of the operating system available are not going to see the real benefits from that next generation SoC.
In Android 2.2 Froyo, there are no dual-core optimizations at all. The system just sees a fast SoC, but Is unable to thread processes effectively. Even in the newer Gingerbread build of Android, there is virtually no support for dual-core SoCs. The ext4 file system added to Android 2.3 sill see a modest boost in the area of I/O performance, but that's about it. Right now, Android on phones does not understand dual-core chips.
A dual-core device might be a really snappy experience, but that's not because of the number of cores per se. The SoC is just fast, even without proper process threading. You can get a similarly responsive device with a regular old single-core SoC. Yes we know, how quaint.
Manufacturers have not completely switched over to making dual-core SoCs as of yet. Devices from Samsung are shipping with Hummingbird SoCs, and HTC is still making use of the venerable Snapdragon single-core chip. These are often extremely fast devices, Every bit as fast as, say a dual-core Moto Atrix in most tasks.
As far as we know, it's Ice Cream Sandwich (ICS) that is going to being true dual-core functionality to Android phones. We have to wonder if a phone like the Atrix is even going to be updated for that long. The Android anti-fragmentation initiative seems to only cover devices going forward, so we have no guarantees that the first generation of dual-core devices will get ICS.
Nvidia also plans to drop Tegra 3 on us this year. So could it be that the life span of Tegra 2 is almost through? If that chips gets left in the dust, it might end up feeling just as outdated as single-core SoCs while the native development heads on to the new chips. Samsung's Exynos SoC is also a mean performer that might beat the pants of Tegra 2 in the coming months.
Now here is something that a dual-core device can actually show off at. Unlike the Android system itself, developers have written games specifically to take advantage of SoCs like the Tegra 2. Because they can access the hardware at a low level, the games can be very visually impressive. Keep an eye open for games labeled "THD", which stands for Tegra HD. These apps just won't work on older single-core phones.
It's these third-party applications that make a dual-core device really worth it. A single-core phone with good software can feel just as fast in the operating system department, but you can only play Samurai II: Vengeance on a dual-core device.
Nvidia knows that gaming is the real selling point of their high power SoCs right now. That's why there is a Tegra Zone app. They can show off all the cool stuff you can do with a Tegra 2 chip. OF course, you don't have to have a Tegra 2 to install this app. All the better to make you jealous.
Battery life and size
We've all heard stories about how the highly optimized architecture for these new chips will reduce power consumption, but you can't get something for nothing. Dual-core chips, while fairly efficient, are still going to use more power under many circumstances. There is a reason the Motorola Atrix has a massive 1930mAh battery.
The Atrix is a little bit bigger and a little bit thicker than it would have otherwise needed to be. The Galaxy SII manages to make better use of engineering and ends up being very slim. Still, Samsung crammed a 1650mAh battery in. This device uses the Exynos dual-core SoC, so we gather it has better optimization than Tegra in many cases. Reviews have reported the Galaxy SII as having solid battery life. Maybe the lesson here is that not all dual-core SoCs are created equal?
We haven't had sufficient time to see how Tegra 2 compares to the rest of the coming dual-core SoCs. The phones we have access to later this year might make better use of such hardware.
Stick with single-core for now?
So with dual-core SoCs, you currently do not get amazing system optimizations, and you might have to deal with a larger device thanks to the battery. Is it necessary then, that you go for the first-generation Android dual-core phones? Ignoring the issue of gaming, you might find a single-core device works just fine for you.
A single-core device with good software can easily feel as fast as a dual-core device with only passable software (ahem, Atrix). The Nexus S and Nexus S 4G are incredible snappy devices, and they run 1GHz Hummingbird chips. Because the stock Gingerbread build is streamlined and well designed, you don't feel a strong desire for a second core.
Is some ways, the dual-core market has some shaking out left to do. Tegra 2 is the de facto winner right now, but new Snapdragons and Exynos chips could end up winning out. Maybe Tegra 3 comes along and makes Tegra 2 look like an abacus. You don't want to end up with the poorest of the dual-core chips, right?
The benefits for dual-core are currently, few and far between. You get better games, and the possibility of better future compatibility with updates. Of course, OEM updates are never guaranteed. Do you plan to get a dual-core phone soon, or are you going to wait it out?