Granted I'm not much of a 3-rail "scale" guy but I've tried the Woodland Scenics stuff and didn't like it. It is foam and I found it to be a bit "squishy" and easily compressed under the weight of O gauge engines. It may be fine for HO but I found it too soft for use with O gauge and my track sunk as the train went over it and rose back up when it passed by.
....and for the love of God DO NOT PAINT IT! You WILL be sorry! (Don't ask how I found that out!)