This site has been discussed at length, in a thread with lots of pages, that started in the AA forum.

The original thread has been erased and only the continuation is now available, even so, it's been halted the discussions.

Second Expert Flyer thread disappears?

The site does work and you can give it a try for five days. If you don't like their service simply inform them so and your credit card gets refunded.

Interest in FT has diminished once access to the info on PNRs has been cut by AA. It remains a good site with valuable information, specially for those who need to check upgrade space, as it's currently the only resource for doing so.

All the other features are available on the net for free with some additional time and efforts.