Overall, this was a big upgrade from the basic model to the 30 so it really does everything the old one did, but a ton more.
The main thing I would say, if you didn't get a map for the unit. I would prefer the basic LCD screen. Adding colour does jack.
I hadn't looked at this function of the unit as I tend to drive to places and walk.
However I gave it a shot this evening. I was out and had a cache still in my unit which I plotted the route. (My old unit didn't have this feature, so I have nothing to compare it to)
My initial thoughts, I wouldn't use this to Navigate around (If solo). Just too small.
Does chirp away at the roads I need to turn down, but that means taking my eyes off the road. (Just as bad as txt'ing).
To calculate the route seemed to be quite fast, maybe 2 seconds at max.
My maps are not really that detail, so I didn't see that issue. (Using the Australian Garmin topo map). So seemed to update fine.
Recalculation seemed not as fluent as I hoped. Driving past a turnoff and it gave no indication that it was re-calculating. But maybe 30's later giving me new instructions.
This is only 1 attempt and it was my first, so take it with a grain of salt. Will defiantly have more of a play with it.