Best:
I haven't got to the best part yet...still building the foundation of the layout. So many more things to try. Having a great time and, so far, I'm really enjoying it but I know it'll get EVEN BETTER. Running trains, scenery, ballasting, buildings... love it. I haven't weathered any locos or made my own decals or scratch built engines or cars yet. And I've just scratched the surface of DCC possibilities.
Without sounding maudlin... probably the best thing so far has been some of the people I've met.
Worst:
The COST!!
Fred
(oh yeah... the TIME too... arg!)