Cheating was a big downside to playing on battle.net though, in my experience. It got so bad that you would enter a game and another player would either crash the game (by dropping a modified ear IIRC) or everyone would be playing with god-mode on. And creating an open, "legit" game only enticed cheaters to join in order to kill everyone. Oh well. My friends and I had plenty of fun playing over IPX and later LAN, or having password protected games on battle.net with people I met in the chat rooms.
I was surprised to find that only a handful of years ago people were still playing on battle.net. Not a lot, but enough to join a couple games and have some fun. Didn't see any cheating, either.
I remember first discovering online mode. Clicking Multiplayer and seeing some sort of "you must be connected to the internet" type message. I started up the dial up connection and tried again and then the world opened up to me.
As much time as I spent on D1 and enjoying myself, it paled in comparison as the gateway drug to SC:BW for me.