After 2mths this is what I think of the TomTom 500 (It was top of the line then. TomTom 910 was released 3 wks ago)
Pros
*Pretty easy to use, I think even someone doesn't know how to use a calculator would able to use one.
*Upload POI anytime I want without waiting 2-3yrs for the next version map. POI can be programmable if you keen, like every winery in Australia, Public toilets, Petrol stations in brand/company, Camping site....etc. And they are very easy to find on the net too.
*Upload celebrities voice, hell yeah, this one is fun, you can have Ozzy Osbourne swear his ass off while giving you instruction on the road.

*Bluetooth hands free car kit. Again my OEM car phone dial doesn't have a kit for my phone. That’s another reason why I bought the TomTom 500 (910 also have the BT).
Cons
*The Map itself is really really really crap, 4 out of 10 times, it had point me to a total different suburb with the same street name, even I inputted the correct address. Next update is due in Oct 06, so I hope they fixed most of the problem as I send tons of email on which street is wrong already.
*The speaker hands free doesn't work until you put it on a cradle. And you have to connect it twice (soft reset) before the dam Bluetooth works properly or it will have crackling noise.
*The instructions isn't the best I’ve use, it will have command like "Keep right and then turn left"

*Accuracy, since these are GPS base only, their accuracy is no where near those OEM or in car version. Without the speed sensor, if you go through a tunnel or in a condense area with lots of building like CBD, it will go "spastic" and would not pin point where I am.
Hopefully this will help for those who are planning to buy a Portable Sat/Nav. Anyone else would like to share their experience on the portable Sat/Nav they got?