Advice: Which Sat/Nav ?

I am looking to buy a Sat/Nav for a present and would appreciate some advice.

I was looking at the 'Navigon Mobile Navigator' as this can be mounted in the car on a bike or handheld.

This was reviewed in T3's magazine and received a score of 3/5. I have also been looking at the 'Tom Tom Go' as this received 5/5 and seems to be the daddy of Sat/Nav.

Has anybody had any experience of the 'Navigon Mobile Navigator'? Is it me a good product? It is a name that I am not familiar with.

Also, are there any other products out there which can be mounted to a bike. This is being purchased as more of a leisure item rather than being used for business travel etc.

Thanks