HTC has a long history of producing well-engineered sliding keyboard phones. We’ve been impressed with its TyTN and TyTN II phones before, and its latest – the Touch Pro – is the best yet.

The first thing to point out is that HTC has discarded the mechanism that allowed you to tilt the screen of the TyTN II towards you. The screen is now flat, whether out or in, but this doesn’t have much effect on its usability, which remains very strong.

As with the Touch HD, build quality is excellent. The keyboard slips out with a good, solid motion and the five-row keyboard underneath is only bettered by the BlackBerry Bold’s Qwerty pad. The keys have just enough profile and travel to ensure that you’re not constantly hitting neighbouring keys when typing.

We particularly like the row of keys just for numbers running along the top, plus the dedicated keys for Tab, Caps, Shift and Ctrl. And although it’s very thick (19.3mm), the Touch Pro’s rounded corners and compact width and height mean it’s very pocketable.

Elsewhere, it’s similar to the Touch Diamond. The operating system is Windows Mobile 6.1 Professional with TouchFLO 3D, and the 480 x 640 screen is excellent for browsing the web with the built-in Opera Mobile 9.5 browser. Other hardware includes HSDPA mobile data, Wi-Fi, assisted GPS, Bluetooth, an FM radio tuner, and an accelerometer for automatic screen rotation.

As with the Diamond, there’s no 3.5mm headphone socket. However, the Touch Pro’s battery life is more impressive, lasting a respectable 73hrs 45mins in our real-world tests.

Another difference over the Diamond is in the provision of memory expansion – there’s 512MB of ROM onboard and an SDHC-capable microSD slot, so you can add up to 32GB. Plus, you can output video direct to a TV, although the cable for doing this is an optional extra.

We really like the Touch Pro – it’s a superb workhorse that’s a great choice for Microsoft-centric email setups – and its price isn’t prohibitive.