Yesterday, I played Inferno with some people. We didn't finish the game, though. People kept dropping out. :) But it was still fun, and it's playable. I got lucky with artifacts; I found the Druid's Bracelet. Drain Life + regeneration is a must-have early on, that's for sure. At the beginning, you need to focus on building Cerberuses (you can generally ignore Lilims and Maniacs, building them only as needed). Eliminate weak neutrals without any losses. Deal with strong neutrals with minimal losses. I didn't build Elites either; I went straight to Lords, and with them, I could break through anything without losses. Tears and Blood are leveled up very quickly, which is great... early on, you can switch to level 1 Tears, and by the endgame, switch back to Blood.