For what it's worth I just switched from BA to BD (thanks to BD for the gold card matching!!), I take around 50 AMS-LHR flights a year, if it's any use to anyone I've noted my experience with them on my first flight BD here:

Booking: BD's site got the departure times wrong, it would let me book a non-existent flight leaving LHR at 20:45 on saturday, even though this flight only does weekdays...
BA's site is (although a little slow) a very reliable booking engine...


Ground staff: BA has a better desk at AMS, the BD desk is in the main hall and when it get's busy there it REALLY get's busy... The staff on the other hand were very helpfull at BD, something that is also true for BA.

Check-in: Got checkin at the ticket desk, even with a gold card the agent tried to stuff me in 1F, needless to say when she also had 2A I took the latter... The folks at the BA desk know me and always try to get me 3A.

Boarding: BD left from gate 18, BA usualy from gate 10, advantage for BD is that after gate 14 at AMS you use central security search, with BA borarding is sometimes held up waiting on the security crew..

Plane: BA uses a 757, BD an A320, BD's seat is a little wider, BA's leg space is a bit better, both not bad. The ceiling videoscreens on BD are not bad but the english-dutch translated safety video is a bit of a drag, it went on for over 5 min's...

Service: The BD flight crew are great people, there were only 6 pax in C so the service was nice, I found the crew I had on both flights nicer and more spontaneous than BA's crew...

Food: BD certainly wins this one, normal food instead of BA's usual platters of seafood and other exotic dishes and cold bread.

Destination: LHR T1 is really a terrible terminal, I'm used to using T4 so the terrible walk from arrivals T1 to the LHR express was way too long, over 15 minutes.. compaired to the T4 walk of just under 4 min's...

Lounges: BD's diamond lounge at LHR is GREAT! Checkin through a card-reader at the door instead of waiting in line at the BA desk is perfect. The lounge was almost empty, I have never been in an empty BA lounge, even the 1st lounge is usually packed...
Great assortment of snacks and drinks...


Conclusion: BD is not as bad as some tried to point out, they were about fl350,- ($150) cheaper than a BA D flight so BD is certainly worth the trouble of a longer walk... I can't wait to try out BD on their new transatlantic flights... To make things even better, I have another month of double points on BD so keeping gold till past 2002 is almost done....