I have the NG Topo! software for Colorado. It works very well, after you get used to the non-standard scrolling mechanism. That's only a minor point though.

The biggest issue for me is the printed map size. Most people can't go bigger than 8-1/2x14 printing with their home computer setups. And I ususally don't have 8-1/2x14 paper sitting around anyway ... only 8-1/2x11. So your printed maps do not cover a lot of area. Topo! adds significant margins on top of this (the newest version is worse, margin-wise, than the older one). Taping seperate printouts together to make a bigger map is no good IMHO.

You can center the printed maps anywhere you want, and print portrait or landscape. This helps out a bit with the smaller paper sizes, but a standard 1:24000 printout on 8-1/2x11 paper is only going to give you maybe 3 to 4 miles of coverage in the short dimension. This usually works for me for day hikes (which tend to be 5 or 6 miles one-way - use the long dimension for printing), but anything much longer would become multi-map problematic.

If you want to take bearings and plot your location on the map, chances are the landmarks you can see to get decent bearings on are off the edge of your map. A GPS alleviates this issue, but takes some of the fun out of figuring out where you are.