I have heard the same thing but then we also saw exploits with the wooden wall.
Stone Walls are seperate from a Stone Castle as well.
The cost is impressive. Then when you combine both Walls and Castle, the Rubies alone are over 291,000.
Basic Cost for one or the other is:
145,613 Rubies, over 42 million pieces of Wood,Ore and Herbs.
Then around 43,000 Guild Runes and Guild Stones are a little less. I can have the exact numbers as soon as the server is up.
The Guild Runes are easy but we always have to wait on Guild Rubies and special events. It can take a very,very long time to get the Rubies but in the end it will be worth it.
Hopefully, my Guild will have one or the other built by the end of this week.

The passageways are smaller and the parapets extend further out making defenses better. The Castle Gates are thicker and harder to take down. The wall gates do come down as fast as the Basic Build.
If nothing else, it looks impressive as (heck). It does have the effect of causing people to stop and go WHOA! (which gives you a wee bit of advantage)

Hope this is helpfull.
I may put a post with all of the requirements.