Having launched its A701 PDA phone complete with GPS last year, Mio is no stranger to hybrid devices such as this.

The A501 is essentially a smaller, slimmer and lighter version that manages to pack in a similar array of technology.

Mio's trademark grey-and-silver colouring and a 2.7in display takes up most of the front panel.

Instead of nestling a directional controller among the shortcut keys under the screen, you'll find it at the upper left-hand side. Quite what the reasoning was behind this decision we're not sure and, although we did find it useful for operating the screen one-handed, it's a bit awkward to use accurately.

Elsewhere you'll find a digital camera shortcut, volume control and full-sized SD card slot, along with mini-USB connectivity. GPS users will benefit from an antenna port at the top, which offers additional navigation flexibility to go with the full car kit in the box.

The A501 is pretty responsive, it starts up quickly and the shortcut keys, along with a sturdy built-in stylus, makes operation fast and accurate. If you're looking at using the device as more of a mobile phone, you can access a traditional phone menu by pressing the Mio Menu control under the display. These can be customised pretty easily, although in most cases the buttons are just a bit too small to be pressed easily with a finger, so you'll find yourself turning to the stylus more often than you might think.

In terms of general looks and usability, the A501 does well, but after a quick look at the specifications, you'll notice a few rather strange omissions. To begin with, Windows Mobile 5 is installed; considering Microsoft released version 6 in February, we think this is a strange choice. You may also be surprised that Mio hasn't updated its mapping software yet - version 3.3 is used which, while innovative and exciting to use when it first appeared, could probably do with a refresh after some recent strong moves from GPS rivals.

As a satellite-navigation device the A501 is solid enough. A nice touch is the windscreen mount's built-in volume extension, which makes it easy to adjust the audio level on the move. The range of options for navigation is fairly limited, though. You won't find many features past the cockpit view and general setting adjustment, but all the most important elements are there. Seven-digit postcode support is available, along with PoIs (points of interest) and adjustable navigation views. You'll also find maps of the UK and Europe supplied on a 1GB SD card in the box.

One issue we've found quite hard to rectify in devices of this size (although it has been done) is the operability of the touchscreen when you're on the move. As we've already mentioned, most keys are too small for easy finger operation, so you'll find yourself attempting to use the stylus instead, which isn't recommended while driving.

Our final gripe is with the lack of wireless support. Bluetooth 2.0 and Edge are available, but despite being quad-band, there's no 3G or Wifi. Other features include a two-megapixel auto-focus camera on the back, a surprisingly loud external speaker and a 2.5mm headphone jack for audio out.

Overall, the A501 is a stylish and highly portable device. If it weren't for the rather poor connectivity and dated software, we'd rate it a lot higher. However, if these issues don't bother you, the A501 offers solid navigational performance and enough phone-oriented features to replace your mobile.