I don't use Datek as my trading account but they seem to be cutting edge with a lot of bells and whistles. You can't beat their RT streamer fed and L-II.
I use DLJ, now called CSFB-Direct. I like their stand alone trading software. It is fast and reliable.
I am signed up for Datek’s free streamer which I use to fire MedVed QuoteTracker’s quote stream.
biomanbaba..I have used Datek for about a year. No problems, executions are fast, site doesn't bog down too much during busy times. I used Watley before Datek and they were AWFUL!