Siri for Android -- sort of
We test a variety of Android apps that offer some of the functionality of Apple's Siri voice recognition feature.
Speaktoit Assistant
Speaktoit
Price: Free
Other versions: None
What it does: Speaktoit Assistant is not Siri, but it's a useful beta that's still under development. It's easy to use and has reasonable functionality. Speak your request and the Assistant answers questions, finds info, launches apps, does social networking, checks the weather, looks at your day's appointments, adds appointments (but can't yet edit or remove them), sends messages, makes calls, plays music, does simple math and more.
Why you might want it: This app offers a number of different functions and decent natural language recognition -- for example, you can usually issue your commands using a variety of phrases. The developer is responsive to bug reports and seems to be working to upgrade and improve the app.
Plus, you can access the app via a long press of your phone's search button so you don't need to find its icon or widget in order to use it -- not unlike accessing Siri by a home button double-tap.
Drawbacks: There was at least one time when Speaktoit was unable to answer a question that it had previously responded to. It also occasionally had trouble connecting to its home server.
The calendar functionality needs improvement, as it only can read one Google calendar in an account (which is problematic if, as I do, you use multiple color-coded calendars to separate business and personal appointments); it also occasionally missed items on my default calendar.
It also took a very long time to find my location when I used 3G or 4G on my Galaxy S II (although it was fine using Wi-Fi). And when it comes to appointments, I'd advise using Speaktoit to open your calendar, not read it to you, because it didn't always find all my appointments (although it did a decent job of adding new events).
Bottom line: Speaktoit Assistant is fun to use and is the speak-back app that I've been using the most. Just remember that it's not a final product yet.
Apps that respond to voice commands
If you're primarily interested in having an app that just responds to spoken natural-language requests without speaking back, there are other apps that are more mature and reliable, but limited in terms of what portion of Siri's functionality they can match.
Google Search / Voice Search
Price: Free
Other versions: None
What it does: Despite the names, these apps do more than just search the Web. Both use Google's Voice Actions for Android to allow you to use your voice to create and send messages (email or text), play music, call either your contacts or a business not in your contact list, go to a website, view a map, get directions or write a note. The difference between the two: Voice Search has a voice interface only; Google Search offers either voice or text input.
Why you might want them: Google's apps offer a handy way to navigate the Web, send messages, get directions and make calls as well as search. They're especially good at making calls -- they first check your contacts and then perform a search for businesses not already in your list.
Drawbacks: There are things these apps don't do that you might expect from an "assistant," such as adding calendar appointments, updating social networks or launching most non-Google apps. Not surprisingly, most information you seek will end up coming from Google, which may not seem any more useful than heading to Google.com.
Bottom line: These apps are worth having and using for many basic interactions with your device, but they're not enough if you want a speech interface that acts more like an assistant.