What's that? Facebook integration? Achievments? (I admit, that is nice)
Other than that, there is nothing the ORIGINAL Battle.net had, that is there.
No text chat/channels which is where people EASILY go in order to communicate before/after games.
Classic games allowed the creation of private games with passwords, or you had to know the game name.
Also, the new Battle.net only shows the MOST POPULAR maps on the top of the custom games list, which means lesser games won't ever get out in the wild, so the first Dota like game, will be the only custom game played.
Second, map publishers are limited to 5 maps, or 20mb total of published maps, can't publish anymore maps after that.
Secondly, the game is so heavily dependent on Battle.net that it is useless offline, can't even use it as a lan based game, Blizzard did state last week, that ALL game traffic will go to the Battle.net server, then back to everyone on a lan if there are 2+ players on your lan, the computers, won't communicate directly. So, if you are on a 1mbps DSL line, and wanna have a lan party, it would be impossible, as the minimum internet connection is like 1.4mbps, or similar, so you would need a rather.. Heafty connection for most areas.