Though to be fair, the specs do it a disservice because when you hold it, it feels big but not ridiculous. Partly that’s because the phone is so slim, and partly because the high-end materials such as the highly tactile shatterproof glass back are so pleasing.

Every detail, down to the aluminium power button, is beautifully crafted – this phone has amazing build quality and looks very premium.

The funny thing is that while Sony and its predecessor Sony Ericsson have made some great phones in their time, those attributes (detail, crafting, build quality, high-end) are much more associated with Sony’s big rival, Apple, and that’s the company Sony’s taking on here.

And, like that other stand-out big phone of recent months, the Nokia Lumia 920, this is a phone that’s so stuffed with features, it’s hard to see where they’ve squeezed them all.

First, it has a screen resolution like you’ve never seen before. The Retina display on current iPhones manages 326 pixels per inch (ppi) and looks glorious. It’s more like a printed page with smooth text and pin-sharp pictures. In normal usage, you can’t pick out individual pixels.

But this takes it to a whole new level. The Xperia Z’s display manages 443ppi and adds even greater realism. It lacks the eye-poppingly bright colour palette of the iPhone but it’s a stunning display.

Second, it’s fast. A quad-core processor means that whatever you throw at it, it manages. Android phones do a lot of multi-tasking, with programs running in the background and this often slows things down. Here, there’s a feeling of a speedy, powerful, responsive phone.

Third, it’s water-resistant. I know, I know, but it’s kind of cool. The headphone socket has a little cap to keep, er, the music dry and other areas are suitably protected. You can put it in two feet of water for half an hour, though I haven’t actually tested this you understand. Anyway, it means there’s no problem texting in the bath, for instance.

Fourth, nobody has made NFC work as well as Sony. NFC, or near field communication, is that contactless data transfer system favoured by many office door-entry systems and Oyster cards. Sony has developed a huge range of headphones, speakers and even a TV remote, that are NFC-responsive. Touch the phone to the portable speaker and the track playing on your phone is suddenly audible in decent quality. Touch the Xperia Z to the TV remote and the video you’re watching on the 5in phone screen starts playing on the telly.

Sony has already launched special tags which use NFC. Touch your phone to the one in your bedroom and it turns the phone to silent and sets the alarm, say.  Tap it on the tag in your car and the mapping app is launched. And so on. NFC is a technology that is about to break through, and 2013 could be its year.

The phone also has a sophisticated battery management set-up so you can kill Facebook updates, say, when juice is running low. And the good thing about having a big screen is there’s room for a bigger battery, too.

But the success of the Xperia Z will depend on how well it can take on the smartphone giants like the iPhone 5 and Samsung Galaxy S III. On first impressions, Sony has a real chance to turn around its fortunes in the mobile phone world.