To give you an idea of some of the things to look for regarding major geographic features, I'm using the Mount Timpanogos area as an example. It's one of the most popular trail type mountain climbs in the state of Utah. I've decided loading tracks on the map overloads it for this purpose, so I'll just point out a few differences.
1:24,000 scale map Downloaded with ExpertGPS
We'll start out with the mapping standard 1:24,000 scale Quad. Notice the steepness of the east face, the narrowness of the ridge, the hiking trails, Emerald Lake and the Emerald Lake shelter. My waypoints from this area would indicate that the map is pretty accurate.
1:100,000 scale map downloaded with ExpertGPS
Next I've included a shot of a 1:100,000 scale TOPO. Note you don't see the Lake or Shelter any more, and that hidden lake is drawn differently. You can still tell the east side of the mountain is the steepest, but you loose a lot of detail.
Mapsource Screen capture with comments added
The Mapsource TOPO matches the USGS 1:100,000 scale map quite closely. Notice however they added POI data for the Timpanogos shelter and Lake. The shelter is misplaced by about 325 feet however, based on the Quad, and my waypoint data that I saved from in front of the shack. You can still guess at the steepness of the mountains, and to an extent the narrowness of the ridgeline. There is some trail data, but it's not as detailed or accurate as what you'll find on the Quad.
Mapsend Screen capture with Comments added
Finally, we have the Mapsend TOPO. Hidden lake is identified as Emerald lake, and there is no POI data for Emerald Lake. Also worth noticing is that there are contour lines running through the Lake shown as Emerald lake. I've found this to be fairly common on the Mapsend TOPO. The Shelter is misplaced positionally by one tenth of a mile, which is somewhat unusual because most of the time the POI data for mapsource and mapsend seems to come from the same data base. If anything, part of the west side of the mountain appears steeper than the east side, which isn't the case, and you would think the ridgeline is wide and flat when viewing this map, which it really isn't. Again, geographic features are rounded, or smoothed out to the point where you would have difficulty navigating via this map and a compass. It's also a little less accurate in many areas, especially when it comes to streams, springs, trails, etc. For a hiker, these potential sources of water could be important, as could knowing where the trails are.