Techno-joy: that moment of pleasure when one finally takes possession of a brand-new gadget, still in its shrink-wrapped box. With a growing sense of excitement, the gadget is quickly stripped of its multiple layers of packaging and plugged straight into the nearest power outlet, its manual lying unseen and unwanted at the bottom of the box. My old Sony Ericsson P800 was no exception.

As is often the case, the source of such anticipation was the abundance of exciting new technical features on offer. The handset boasted an impressive list: not only was it a phone, it had the screen of a PDA with an open, stylus-driven UI, built-in HTML browser, MP3 player, camera, games capability and hundreds of downloadable applications on offer. It was leaps ahead of my comparatively outdated Nokia 8310, and presented a seemingly perfect solution to all my personal technology needs. Over the next few days and weeks I explored all of its features in detail and was occasionally rewarded with the delightful discovery of an unexpected piece of functionality or interaction. And, for a time, all was well.

But the fairytale was not to last. Little by little those aspects of the device's interaction that had so delighted me in the early days started becoming less appealing; what had initially seemed good slowly degenerated into mildly annoying and then downright irritating. The handwriting recognition that had initially seemed so convenient soon became a burden when I realised that replying to an SMS while on the move was almost impossible. Similarly, the stylus-driven interaction of the user interface required two-handed use to accomplish anything significant, thus presenting another source of much frustration.

It wasn't long before I found myself yearning for simpler times. Or, more precisely, for a simpler phone: one with real hard keys I could feel with my thumb, with mechanical feedback and T9 so that I could text on the move - one-handed and by feel - without the risk of walking into a lamppost. I wanted a phone that permitted me to answer calls without having to look at the screen; a phone that allowed me to redial a number without reaching for a stylus. I had come to the realisation that, in some cases, less really is more.

Which is why I fell in love with my next purchase: an original third generation iPod. It was a perfect example of a device that was optimised for a single function, and its growing market share reflected the public's appreciation of its simplicity of style and design principles. Later, when I upgraded to an iPod Photo, I was slightly anxious that the extra features might spoil the simplicity I so admired in the original device. However, I was delighted to find the new image-handling functionality was implemented in a graceful and discreet manner, enhancing the device without complicating its original feel and interaction.

Unfortunately, this philosophy of simple design does not often seem to be reflected in today's mobile devices. On the contrary, the mobile phone has progressively become a dumping ground for any and all newly-commoditised technologies that were previously the domain of dedicated devices. Cameras, FM radios, digital audio players, and now even televisions are being included in handsets whose traditional core purpose was the handling of voice calls and text messaging.

The inclusion of all this new technology is not a problem in itself. Rather, the problem lies in the way in which all these functions are made available to users. Features of secondary importance are often placed at the same level of interaction as the features that are key to the device's core purpose. Even worse, the device's core purpose has often not been identified in the first place - is it a camera, a phone, a PDA or a Web tablet? Should it be easier to answer a call or take a snapshot? During my work in the field, I have even heard someone suggest removing a new phone's Send and End keys in order to promote the device's multimedia 'identity,' with complete disregard to the phone user's need to, well, make and answer calls quickly.

This may be why today's mobile market seems to be flooded by complex devices without any specifically identifiable 'soul': Frankenstein-like hybrids assembled from the body parts of other devices, afflicted by bizarre key layouts, deeply nested menus, and Byzantine user journeys. These devices have little discernible prioritisation of purpose, and their interfaces fail to account for the fact that not all features are used equally. They end up sacrificing good design at the altar of have-it-all technology.

In recent years, the challenge in designing interfaces for mobile devices has shifted from finding ways around technological limitations to finding ways around technological overload. Consequently, more so today than ever before, it is important for designers and handset manufacturers to place more effort into first identifying the core purpose of any new product and then building everything else around it.

With everything from mobiles to portable game consoles becoming one blurred mess, it may be time to take a leaf from Apple's iPod and design new products with strong, identifiable characters and purposes. It may be time to give new products their souls back.

Giuliano Maciocci, a UI Designer at Mobile Innovation, the London based user interface designer, product integrator and software developer for smartphones and communicators.