If you were to go with a regular numbering system, the big question is why this isn't the Lumia 725 - the increased CPU speed and storage capacity, plus the 512 MB of memory, means it fits the curve between the Lumia 720 and 820 far more than it does between the 620 and the 720. Throw in 4G capability and it becomes even more curious.
But trying to position this handset purely from a numbers point of view misses the point completely. This is a handset that is designed to slip into a specific marketing slot, not a nice arithmetic progression on an Espoo Whiteboard. It's being positioned by emotion, fashion, and economics. With those criteria, slightly better than the Lumia 620 is the exact destination for the Lumia 625.
Big is the fashion nowadays. Big and thin. And the Lumia 625 certainly delivers that with a 9.15mm frame caressing the 4.7 inch screen. Put this next to the rest of the Lumia range and on first glance I think the 625 will be the first to catch the eye - simply because it fits in with the PR message of what should be expected.
But the price! SIM free, it's around half the price of the Samsung Galaxy S4, it's almost at the impulse buy level of £200, and it sports 4G connectivity - with the rest of the UK networks gearing up 4G coverage to join EE in the UK, having a low cost 4G handset is vital for Nokia. The monthly contract price in Europe is going to be close to free with a small monthly commitment. And even the small subsidy that comes with Pay As You Go is going to make the Lumia 625 into an attractive handset. I reckon it'll be heading towards the sub £150 mark come Christmas.
The Lumia range is already picking up traction in certain social circles that aren't normally considered by the geekerati - the school playground. Windows Phone covers the social media bases, the lower end handsets on Pay as You Go are affordable and do not feel underpowered or crippled (note the prominent display of WhatsApp and TempleRun in the promotional video). I can see the Lumia 625 being a very attractive option for many.
But I don't think that Europe is the primary market for this handset (even though I suspect it's going to do very well). The Lumia 625 is going for the Asian and Indian markets. Here the lower cost of the handset is balanced out by economic forces. The 625 has the look of a high end phone, but it's going to be easily within the financial reach of the mid tier masses.
Now that Nokia have sorted out the kinks from their Windows Phone platform, and are happy with a common hardware base over the range, they can focus on leveraging the advertising that is around the Lumia name and ensuring that every handset in the portfolio has the benefit.
Half the marketing for the Lumia 625 is already done. Windows Phone has a growing reputation of delivering a very good user experience with hardware that is not at the cutting edge. The Lumia 625 specs, notably the 1.2 GHz dual core processor paired with 512 MB of RAM, would struggle to run a buttery smooth Android experience. That's not the case with Windows Phone. The Lumia 520 and 620 have put in some sterling performances for me, and they have an even slower CPU (a 1 GHz dual core).
Size is not everything - we've been down the 4.7 inch WVGA screen route before with the HTC Titan, but that was marketed as a flagship device. The Lumia 625 is not a flagship, but it comes with more software, more support, and more cachet than HTC's monster of a Windows Phone could ever muster.
On technical merit, the Lumia 625 is a cracker of a handset; on styling and fashion, the Lumia 625 also delivers - the ability to switch out the casing as fast as you would switch out a shawl should not be discounted; on positioning and cost, Nokia have found a Lumia 625 shaped gap in a number of markets around the world. If you've ever wondered Nokia's ecosystem plans for the Lumia, the 625 illustrates this in a nutshell.
It's not a sexy handset, and it's not going to be one that is picked up by the glossy gadget magazines or used in a tabloid shoot-out to find the next 'best phone since sliced bread'. That role belong to the Lumia 1020. The Lumia 625's role is to sit proudly on the retail shelf, ready for the moment when someone is looking for an affordable handset that meets the fashionable expectation of a modern smartphone.
Quietly, with little fuss, the Lumia 625 is going to sell in significant numbers, and the low-end Windows Phone handsets are going to help increase the platform's market share far more than the high-end gee-whiz smartphones.