Whats wrong with Foundry Networks?

I've seen on this list, and from many other places a generic hatred for
Foundry -- with comments like "It's IP stack is just plain broken".
Whenever I ask people for specific examples, I get none.

Now, I have seen plenty of bugs in Foundry -- but all in all, I think
Foundry BigIron is the best router you can get, given the price. I am
now using BigIron 8000's to do most all of what I used to have 6509's
doing, and I haven't regretted the decision to switch for one second (I
did use a mix of foundry and Cisco before -- and regretted the decision
to include Cisco at all)

Anyone care to share why they feel Foundry is inferior?