I drove to Toronto and back over the weekend. I knew the way, but I used my Garmin nüvi 255W (see previous entry) to navigate. Of course, there were some quirks. I have the following observations about what it recommended:

1. It’s deeply schizophrenic about the express and collector lanes on Highway 401 in Toronto: it directed me to switch back and forth between them. I knew better and ignored it.
2. It will not hesitate to recommend back roads as shortcuts — even deeply twisty ones with single-lane bridges. There are times when sticking to main highways is better.
3. The navigation algorithm does not let you deviate from the highlighted route without it squawking about it. I decided to take an alternate route that I knew would add a only couple of minutes. It instructed me to turn around and get back to the original route long after the new route would be shorter; my ETA suddenly improved by 15 minutes once it accepted the new route.

This was using the quickest route option. There will, in other words, always be navigational quirks. It’s always a good idea to know enough about the route to know when to ignore your GPS’s advice — but then I’m not saying anything new here.