Just thought I'd share my short views of the Dungeon.
Heh, I'm very obviously biased since I've been running this thing for better than a year now. I like it. I'll try to give a fairly even handed rundown of the parts that we've actually played here to give people an idea of what it's like. Just remember, yes, I am a fan.
Overview
This is, as advertised a honking big dungeon crawl. The WLD is split into 15 regions, each self contained, each with its own storyline and "feel". The basic premise is the party will enter in Region A and cannot leave until they find an exit, many, many levels later. This, of course, brings with it a host of issues - supplying is difficult, food, water, survival, character replacement - are all problems the party must face.
My group has travelled through Regions A, B, C, G and now K. You will not actually hit every region during play. At least, you're not really meant to. Each region has a level range, usually 3 character levels, so, once you've progressed to a certain point, it would be kinda pointless to backtrack.
I play 3 hour sessions and it has taken me about 10-15 sessions per region. Some people are obviously faster. One of the other DM's is most of the way through C after 20 sessions. YMMV and all that.
Region A
This is the introduction region. It has some strong bits and some very weak bits unfortunately. On the strong side, there are several groups with which the party can interact rather than simply kill - a group of orcs, kobolds or troglodytes. Allying with any one group will make the other two enemies. The layout of the region is very nice with very few mistakes.
On the down side, the region is VERY repetitive. There are room after room of darkmantles and rat swarms. This can lead to a really grinding experience of "We open the door, kill the critter go to the next door".
I found that adding a few creatures and changing a few bits really made a big difference. I added a trapped angel in one area for the party to interact with and a crypt thing in another area which split the party and teleported them to random areas of the region. That went over quite well.
Region B
I have very mixed feelings about this region. It has some very cool ideas - a goblin empire that worships a bizarre statue, numerous traps and goodies, and some really fantastic set battles. On the downside, the map for this region needs work and there is some truly piss poor editing. In my view, fantastic idea and can certainly work, but, needs a fair bit of handling to keep running smoothly.
Region C
My favourite region so far. An insane dragon, dead wizard, the remains of titanic battles and all sorts of other goodies. There were almost no mistakes that I could find in this region and the storyline here is really attention grabbing. Entering a massive chamber with chains the size of a bus lying broken on the ground is just a great memory. And I think the battle with Nardarik the Black is something my players will remember. I know I will.
Region G
This region ties for favourite for me. A massive battle between angels and demons with all sorts of evil chewy goodness mixed in. This region is sweet because it has just so many things in it. The party can interact with the creators of the Dungeon, and they can likely talk to the demons as well as both sides try to recruit. Bloody great battles too.
Region K
The party has just entered here. Honestly, doing the prep work for this region, I was left feeling rather cold. One nice set piece battle and some rather poncy encounters. However, I think this might be one of those "Looks bad/plays good" type things. The party has rescued a lizard folk tribesman and returned him to his tribe. This has led to lots of interaction and role play. Nicely different from dealing with the angels since the lizardfolk and the party are so much more on equal footing. We've just scratched the surface here, but, I'm thinking that this region, although likely considerably shorter than others, might be a whole lot of fun.
And hey, any time you get to go toe to toe with a dragon, it's gotta be not bad right?