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Emini is right, IB's support sucks ass and their charts aren't that good either. I was gonna open and account with them but ended up doing so with a Canadian broker. I pay for ECNs but given the fact that my orders aren't large, my orders typically fall under $10 each way so I don't mind that.
But other than that, and Emini would know best, IB also allows for API trading system development (which costs a bit more to execute by the way), which could come in handy if you're trained in mathematics and programming. Do people use IB for that kinda thing Emini? I do eventually plan to trade using quantiative methods (that could mean almost a decade as I'll need a job first).
An alternative to IB could also be Quotetracker. Those guys can integrate your account with IB and give you only those features that you have in IB. They're owned by TD-Ameritrade and if you have an Ameritrade account, QuoteTracker's premium membership is free for you. I love QT's charts. It has a really nice layout and your watchlists are really well laid out. I've used my canadian broker's account to log into QT and trade. It's really nice.
Here's something I noted about trading platforms: a large number of discount brokers that offer access to the markets via some desktop trading platform do so through a company called Nexa Technologies. I can't say so about the US, but in Canada, ALL of the major discount brokerages, even TD Waterhouse's trading platform has been developed by Nexa. Check out their producs. A lot of the time people find themselves using the same platform even if they switch brokers. Be careful 