2 players are against each other. I think one could use it for normal D*&D if you wanted, might be a pain to assemble lots of different battlefields though.
I love using heroscape tiles for 4e D&D. They are easy to put together quickly for a random outdoor adventure, and the raised elevation of the heroscape tiles gives a real 3-D perspective. I did a duegar ambush around the Minotaur Gate of Thunderspire Labyrinth just last session, and the Heroscape Tiles allowed me to make a scene that looked like the picture of the gate in the module.
The hex system seems not to make much of a difference for how the game plays. After all, there are only 5 players in a party so flanking isn't an issue. The only real issue seems to be with large creatures, which have to awkwardly straddle three hexes.
I wish there was square plastic interlocking tiles for interiors, I'd buy those over the dungeon tiles in a heartbeat. The dungeon tiles themselves just leave me feeling frustrated. They never stay together, and they never seem to have the right shape for what I want to do.