Google has been working on improving the responsiveness of Android through Project Butter. Devices such as the Galaxy Nexus and Nexus 7 really showcase the benefits. Google says Android 4.1 has a higher refresh rate and triple buffering in its graphics pipeline, two things that should make visual transitions appear smoother.
In reality Google's performance changes to Android 4.1 result in a modest improvement in general usage, the screen rotates a tad faster but Android 4.0 was no slouch, even on the Galaxy Nexus' dual-core processor. Of course we wouldn't decry any performance improvements and this is the type of behind-the-scenes work is something Apple has done with iOS to create a very high quality user experience. It also suggests Google is not just relying on extra processor cores to boost performance of Android.
Google has beefed up Voice Search to compete with Apple's Siri and Samsung's S Voice. The service does recognise requests such as "What is the weather" or "How to root Galaxy Nexus" which is impressive, though we still wouldn't use it in place of a keyboard. Accuracy is still hit-and-miss and at times voice print analysis can take considerable time.
Google's work on improving Android performance is starting to pay off, with performance on existing hardware showing improvements.
There wasn't any noticeable boost to battery life, which is a disappointment and although Android 4.1 isn't the step change Android 4.0 was, we would still encourage users to upgrade.
Google's Android 4.1 is a very good update to Android 4.0 because it boasts big improvements under the skin while tweaking aspects that were already very good, such as the notification system.
The biggest change for most users will come from the lack of Adobe Flash support but a number of websites have moved to HTML5 and even Adobe has stopped developing the software for mobiles. In our testing we didn't find the lack of Flash a problem, but for those that depend on Flash, Android 4.0 is the only choice.