It seems like just yesterday I was sitting at my desk, new phone in hand, typing out my review of the Xperia Z2. It was Sony's flagship that many of us thought would take the company through to the end of 2014, yet here I am, not even six months later, reviewing its successor. Either Sony has a ridiculously fast release schedule, or the technology market is moving at an ever increasing pace. I'm thinking the former...

Compared to the Z2, Sony has made some minute changes in the Xperia Z3. We're looking at a very slightly upgraded Snapdragon 801 SoC, a marginally smaller 3,100 mAh battery, a thinner design, and a few tweaks to the software. You'd be forgiven if you thought the Z3 was in fact the Z2, considering the camera and display are essentially the same as well.

But the Z3 isn't designed as a direct upgrade for those people rocking the Xperia Z2, or even last year's Xperia Z1. Instead it's clear that Sony has been tinkering with the perfect smartphone formula, crafting something that can provide a balance of design, performance, camera quality, and battery life. Sony wants this to be the ideal upgrade from the Xperia Z, and on top of that, they want the Z3 to be so well made that users of competing products might consider a switch.

However, I do have to wonder about Sony's strategy of releasing a new phone every six months or so. The launch of the Xperia Z3, which is nearly identical to its predecessors, feels a little underwhelming when the market just went through another iPhone launch. On top of that, Sony's fast release cycle quickly devalues products that some people have just purchased, which affects the level of buyer's remorse in the Sony camp.

From an outsider's perspective (I'm not party to Sony's marketing strategy), a new flagship smartphone every six months seems a too fast, with many companies getting it right with a yearly schedule. However, if these small increments have finally allowed Sony to really hit the nail on the head and deliver a top-notch product, I'll probably forgive them.

The Xperia Z3 still features Sony's signature design that started with the original Xperia Z nearly two years ago. It's mostly a thin rectangular slab with a display centred on the front, and minimal design cues extending to the clean rear panel. Both the front and back are constructed from Gorilla Glass 3, giving the smartphone a high-end look and feel at the expense of increased fragility over metal or plastic.

Despite the inclusion of two slabs of glass, the Xperia Z3 feels very solid. The body is extremely tough with little (if any) flex, helped by the aluminium edges that increase its strength. The aluminium isn't just for structural integrity though: it makes the handset feel like a nicer, higher-end product in your hands, while also improving the aesthetics through a pleasant shimmery silver that complements the white body. Like previous Xperias, the Z3 is also available in black as well as green and copper.

The main visual difference between the Xperia Z3 and the Z2/Z1 is the refined design of the edges. Sony has added in a more accentuated curve to what used to be a pretty harsh, flat edge, noticeably improving how the phone fits in your hand. When these ergonomic changes are combined with the thinner and lighter body - 7.3mm and 152 grams, down from 8.2mm and 163 grams in the Z2 - the Xperia Z3 is the easiest of the full-sized Zs to operate.

While there are new placements for the two front-facing speakers, notification LED and front-facing camera, I still feel like the bezels on the Xperia Z3 are too large. Those that flank the display to either side are fairly standard, but those to the top and bottom extend beyond what seems reasonable for the display size. Shrinking these bezels down would improve the phone's display coverage (71%) and make it easier to handle.

The Xperia Z3 is still water resistant, packing an improved rating of IP65 and IP68. This indicates the smartphone is dust tight, and can withstand low pressure water jets and immersion in fresh water up to 1.5m in depth for 30 minutes. For those that frequent pools or want to game in the shower, this is a handy feature, though keep in mind that the Z3 is not resistant to salt water. In other words: don't take it into the ocean, or you might find the salt will corrode the internal components.

The choice to water proof the Z3 means there is a flap to protect the microUSB charging/data port. Yes, you can charge the Z3 via the magnetic dock port on the left side, but if you don't want to shell out for the compatible dock or proprietary charging cable, you'll have to deal with the annoying cover. Luckily, it feels sturdy and secure, so it's unlikely to break off any time soon.

Sony has also rearranged the position and grouping of the two flaps on the Xperia Z3, improving usability. The left side features just the microUSB port, while the right flap contains both the microSD slot and nano-SIM tray. Although it can be tricky to use the nano-SIM tray, the grouping of the slots makes more sense than having the USB flap also uncover the microSD slot.

The right side also packs the circular power button, which is slightly too small and too low down (though these are minor complaints). Below that is the volume rocker and handy two-stage camera button. The left edge has the magnetic charging port that both looks bad and feels bad, and a small charm connector at the bottom. The top edge has the exposed 3.5mm audio jack.

The main thing to take away from the design of the Z3 is that Sony has managed to make small changes that add up to a refined experience. Nothing massive has happened in the six month period between the launch of the Z2 and Z3, but the Xperia Z3 feels undoubtedly better to touch and use.