The GPS-lock time is indeed puzzling.
The N810 is the first GPS-device I've owned, so I have no base to compare, but...
At a friend's house, I routinely get lock inside of 30 seconds.
In my own front-yard it can take 3 to 4 minutes.
Inside my house, it will NEVER get a lock, but if I bring the 810 inside already GPS-locked, the lock holds firm, rather than degenerating and breaking off as I would have expected.
Although, as I write this, I just achieved a GPS-lock from inside my house in about 20 seconds.

Works great once it is locked, but the lock-on behavior is frankly annoyingly erratic.