Don't let the recent news that Facebook's growth is slowing fool you into thinking that the social networking phenomenon's popularity is one the wane � Mark Zuckerberg's creation continues to dominate the lives of millions upon millions of people worldwide, and you need no further indication of its power than the launch of not one but two 'Facebook phones' from the Taiwanese giant HTC.

Announced with a reasonable degree of fanfare at Mobile World Congress back in February, these two devices boast a unique Facebook button which allows you to post items to your wall in double-quick time. Is this gimmick enough to make them stand out in a rapidly-crowding Android marketplace, and can it give HTC the edge over rivals such as Samsung, Motorola and � of course � Apple? We've had both the Salsa and ChaCha for a while now and intend to find out.

Purely from a hardware perspective, the two siblings couldn't feel more different. The Salsa is your typical touch-screen device, with the aforementioned Facebook button being the only physical input on the front of the phone. The rest of the handset is dominated by a 3.4-inch capacitive display. Around the back you'll find a 5 megapixel snapper and HTC's signature unibody construction � although in truth, the design used here isn't as all-encompassing as that seen on the HTC Legend and HTC Desire HD � the bottom of the Salsa is made out of plastic rather than brushed metal.

The ChaCha is a different beast entirely. The focal point of the phone is unquestionably the full QWERTY keyboard, a clear attempt to tempt BlackBerry fans away from their beloved phones. The presence of all those lovely buttons has forced HTC to rethink the design of the ChaCha slightly; the screen is a landscape affair, with a size of 2.6-inches.

To make typing a little more comfortable, HTC has given the ChaCha a unique 'bend' in the middle � at first it looks rather odd, but it takes just seconds to become accustomed to its bizarre shape. Like its sibling the Salsa, the ChaCha has that all-important Facebook button right at the bottom, within easy reach of your twitching thumb.

The way in which the Facebook button works is the same across both handsets. If you press it when you're on your home screen it opens up a dialogue box which allows you to post something directly to Facebook. Links to your photo gallery and camera appear, allowing you to swiftly snap a photo and upload it to your account.

Elsewhere, the button is context-sensitive. For example, if you're browsing a web page that you'd like to share with others, tapping the Facebook button automatically prepares the link and allows you to enter a little textual description before submitting it to your wall for posterity.

Similarly, if you're watching a video in the official Android YouTube application, the button will seamlessly link the clip in question to your Facebook account. The fun doesn't end there, however � when you're listening to a piece of music, prodding that friendly blue key will let your friends know exactly what it is you're tapping your toes to.

Clearly for those who count themselves as heavy Facebook users, such functionality will be very welcome indeed. Being able to post items to your wall with just a button press is a truly appealing experience, although it should be noted that the Android operating system already makes it incredibly easy to perform this task via its 'menu' button. The big benefit here is the tactile nature of the interface � pressing a physical button to share content with the masses never seems to get old.

However, we worry about what kind of effect all of this sharing is likely to have on your social standing. Everyone likes to peruse interesting information and see holiday snaps, but when it gets to the stage when you're posting data up about what song you happen to be listening to at that precise moment in time, it comes perilously close to being little more than spam. Clearly, the use of this much-hyped key should be carefully regulated to avoid annoying all of your Facebook contacts.

Social networking aside, neither the Salsa or ChaCha really set the world alight when it comes to raw specs. Both run on a 800mHz processor (which will be below entry-level in the eyes of many Android users) and there's no fancy tech like NFC or dual-core chips.

Even if such humble tech doesn't dissuade you from making a purchase, there's the question of which handset to choose. Despite its awkward appearance, it's actually the ChaCha which pleased us most. That QWERTY keyboard is an utter joy to use, making typing a breeze. Granted, the dimensions of that landscape display can cause problems when it comes to compatibility with applications (games like Doodle Jump require you to hold the phone on its side to play), but if you're looking for a device on which you can quite happily pen an entire novel without getting thumb-cramp, then this is it.

That's not to say that the Salsa isn't worth a look, though. Thanks to its touch-screen focus, it's more in line with phones like the Samsung Galaxy S II and the HTC Sensation � albeit not as powerful in technical terms. It has little problem running most applications, although the relatively slow processor can make some 3D titles operate a little slowly.

Ultimately, both phones are going to find plenty of favour with rampant Facebook addicts. That context-sensitive button is genuinely useful, and HTC's typically polished Sense UI makes using these handsets intuitive and enjoyable. It's also worth noting that both phones are running Android 2.3 � also known as Gingerbread � which is the latest edition of Google's mobile operating system.

It goes without saying that HTC will look to expand its portfolio of Facebook devices in the future, so both the Salsa and ChaCha should be considered 'trial runs'. Also, veteran smartphone users may find both severely lacking in pure technical muscle, which leads us to suggest that it may be worth waiting to see what a next-generation Facebook phone from HTC can bring to the table. However, if you're on the lookout for a mid-range handset with social talents and can live with relatively humble tech, either of these will fit the bill.

HTC Salsa

Pros

• 3.4? Capacitive Display
• Unibody Construction
• Facebook Key for Quick and Easy Access

Cons

• Below Average Specs Sheet
• Back Feels Plastic

HTC ChaCha

Pros

• Excellent QWERTY Keyboard
• Curved Design for Easier Typing
• Facebook Key for Quick and Easy Access

Cons

• Below Average Specs Sheet
• Landscape Display Might Cause Compatibility Problems with Certain Apps

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Damien McFerran is a tech and video game journalist who has contributed to Eurogamer, Pocket Gamer, GamesTM and Retro Gamer. He's also the editor-in-chief of Nintendo Life, one of the net's biggest Nintendo-centric websites