In my limited experience its fairly straight forward and not to bad - less than 2 hours total (about 1/2 an hour (or less) the European side and one to one and a half the Russian side).
- Ride to the head of the line of trucks (or you'll be there for days) - they won't object.
- Some borders shut for an hour at lunchtime.
The Russian side of the border, which is the one everyone seems to worry about, was no real problem in my experience. As long as you smiled and were polite guards were really friendly and helpful.
Enjoy your trip.