If you keep close tabs on the smartphone scene – and PC Pro’s reviews section – you’ll know that we weren’t too impressed with HTC’s response the iPhone 3G, the Touch Diamond a couple of months ago.

We liked the fact that it buried most of Windows Mobile’s ugliness under an attractive, finger-friendly touchscreen interface, and we liked its fantastic VGA screen. We were also keen on its fantastic web browser – Opera Mobile 9.5.

But we hated its sluggish performance. The whole point of touchscreen interfaces is that they should be responsive, but this was anything but. Hit a control on screen and, like as not, you’d have to wait a second or so before anything actually happened. It was one of the most frustrating phones we’ve ever had the displeasure to use.

Would the same issues afflict its big brother – the Touch Pro, which arrived in the Labs today?

Essentially this is a Touch Diamond with a slide-out Qwerty keyboard bolted on, and a few other tweaks, but initial impressions are good. Responsiveness is up, despite the phone boasting the same 528MHz processor. Perhaps the increased RAM, up from 192MB to 288MB is responsible for this.

The battery capacity has also been increased from 900mAh to 1,340mAh, which should result in longer periods between charges, but it’s not as dramatic an upgrade as we’d hoped for.

Elsewhere it looks a solid handset. Features are, as you’d expect from a flagship HTC phone, second to none, with fast HSDPA mobile data (for speeds of up to 7.2Mb/sec), a three-megapixel camera (this time with an LED flash) and VGA video phone, a GPS receiver, Bluetooth 2.0 an, of course, 802.11bg Wi-Fi.

Build quality seems excellent too – the Pro has a decent heft to it, and the sliding mechanism is smooth and the the keyboard it reveals seems of decent quality too. It’s also worth noting that HTC has done away with the nasty, glossy plasticky rear of the Diamond, replacing it instead with a thicker panel covered in rubbery, soft-touch black plastic.

One disappointintment is that it’s a very chunky, phone, measuring 18mm thick. We were expecting something a little more svelte.

But the thing that took our breath away wasn’t the looks or the build quality it was finding out how expensive this phone is. SIM free, it’s set to cost a whopping £451 (exc VAT). Is it worth it? Can any phone be worth spending that much money on? Be sure to check back at the beginning of next week, after we’ve given it a thorough going over, to find out…