The title says it all. This product is simply a must have, especially if you play d&d 3.5 whose combat system is really mini oriented.
Two suggestions though. It is a great product but it could be improved if
1) The hexagon side is replaced by a square grid so you could use both sides.
2) A 10ftx10ft grid is overlaid on the current 5ftx5t one. Make the 10ft lines just slightly thicker. 10ft is usually the scale used by most scenarios to draw plan.