Is it worth upgrading from Navigator 3 to Navigator 5?

[Buster44]

I currently have Tom Tom Navigator 3 which I have been very impressed with.

I have recently changed my pda to a HW6515 but now find the menus a bit bunched/unreadable as the screen is now smaller.

Is it worth upgrading to Navigator 5? What new features does it have? Is there an upgrade route offered or do I have to buy the software at full price?

Any advice very welcome.

[Buster44]

Thanks. Checked the Tom Tom site and upgrades finished in November, but a new upgrade programme will start later this year.