I mostly use Datek to use Streamer - I sometimes trade options, and it's useful to see the bid/ask trend of the underlying. I use IB preferentially, but if it looks like IB is routing to PHLX, I switch to Datek for that trade, because their software doesn't seem to get hung up if you try to cancel or replace before 2 minutes. IB's charge for cancelling a directly-routed option order means it's very costly to chase a fast-moving offer (like during MRK's rally one day last week).
Not much to add to the Datek comments people have already made, except that if you don't get the answer you want from the help staff, just ask again and it'll probably work.
For instance, I qualified for their frequent-trader program, which consists of free news and level II quotes. The first time I asked how to get my status upgraded, I got a boilerplate description of the program. The second time I asked, I was told they periodically check for eligibillity and the next time would be at the end of the quarter. I ignored that answer and asked someone else, and got upgraded immediately.
They
do seem to be rather defensive about their software, though. Even when I give fairly specific bug reports about certain quotes being wrong under certain reproducible conditions, I'm always told all systems are working fine and I should clear my browser's cache.
What they need, other than the ability to contact more clueful help staff, is an actual trading platform and direct access for options.
At least they don't slow down the web pages with third-party banner ads like a certain other b*roker.