I've been using IB for almost 2 years.
At that time (2002), I think it was the best broker for small- to mid-volume traders (under 10.000 round-turns per month). And think IB is still the best "main broker" option for this type of trader.
Since the start, I considered that there is no "real" phone support from IB, so ever since I maintained backup brokers. I never had to use them though, except one time, when Globex went down in Apr-2003 but pit kept trading.
Only time I tried called them (along with a few 1000s others I guess) was when they announced via bulletin they'd "suspend my account due to funds, unless I called them at XYZ number".
The REAL SERIOUS FLAW with IB was several occasions where Globex resting stops (i.e. the usual "simulated stops" submitted via the TWS and held on IB machines) were not executed by IB. Price just traded through them and they didn't get triggered. One such period was mid-2003 (Thu,Fri and Mon) and again around end-2003 (for 1 day), if memory serves right. This was IB's bug and I lost a few thousand $ overall. I never experienced anything similar since.
Overall feed and uptime has been very good in my opinion. I run TWS every day during RTH and get a few disconnects per week (due to momentary Internet outage in the path) are re-connected automatically within a few seconds. IB feed is faster than all data feeds I checked (understandable, as it's a snapshot feed, whereas a "real" feed like esignal has to send all ticks)
And the overall platform was (and is) LIGHT YEARS AHEAD of the PATS Jtrader alternative offered by Man or Refco at the time.
Overall, with the exception of the "simulated stop bug", my experience with IB has been very positive.
I plan to look into the XTrader platform, although I'm not into the micro-scalper (for a few ticks in a few minutes) trading style, so I'm not sure what the benefits are.
