24 hours a day someone is available for a live chat. If I remember correctly, hit the 'help' button twice and a chat window pops up where an actual live user answers questions. These questions can range from not understanding how to use some feature to help locating data and beyond. If the discussion is getting too involved for chat, the support person won't hesitate to call you.
Bloomberg bundles in several interfaces beyond their GUI. The excel plugin, which updates your spreadsheet in real time is fantastically easy to use. Programmers can use official apis in various languages to query static data or subscribe to real-time feeds (although exchange contracts need to be signed separately).
Bloomberg symbology is hugely important. People outside the industry might find it absurd that it isn't very easy to know the _name_ of the instruments being traded. Are you trading AAPL? Is it the one traded in US, Europe's various exchanges or anywhere else in the world? Are you using cusip? isin? sedol? reuters symbol? bloomberg symbol?
The bbg GUI looks like it belongs to the mainframe era, but the user interface is actually very convenient for people who rely on it daily. Simple commands bring up the data you need immediately, no need to click though a bunch of menus.
Upstarts will have trouble toppling bloomberg for another reason: vendor contracts are a mess. Getting the right to distribute data is very expensive. The contract costs a fair chuck of change, then the distributor must keep track of every single end-user of the data (which associated costs of technology, legal, etc.) This is the case with very standard data feeds, like New York Stock Exchange! A great deal of data comes from markets where deals are done 'over the counter.'
I don't say all this to discourage anyone from trying. I've thought about this problem a bit and it certainly will be a very interesting project for whoever tries to get in the game.