Mudster, I have to say I've only played with/used the unit on a couple of occasions but I can't say it's cheapness carries any super apps.
The routes I've used so far are adaptable to add way points no problem; I've done it directly into the unit. I think you get what you pay for though. It's not Garmin or TomTom.
There is a link for updates (don't know if they're free) and extras for the unit. 'naviextras'.......
I bought it to make getting lost impossible and boldly going where I've never gone before. You still need a map (or star chart) for that!