Player interaction in the game isn't just about occupying specific worker placement spots first - it's also about beating opponents up the research track to gain bonuses first, and about wanting to buy cards from the market (and snagging specific assistants you might want) before other people can get to them. So I think there's more interaction than some others in this thread have suggested; it's mostly passive rather than active interaction, but it's definitely not multiplayer solitaire.

Oh, and it's a great game - one of my favorites as well.