I don't know how closely everyone's following the 4th Ed thing ('cause if you are, this is old news), but just in case: The 4th Ed Pit Fiend statblock is up at Wizards.
The first few pages of the enWorld thread do a decent job of explaining what the numbers mean.
What did you expect though? I mean, pretty much everything about four E so far seems to be meant to appeal more to people who don't like DnD.
Notice it's a Religion check, not Knowledge: the Planes. (IS there still a Knowledge: the Planes in 4e?)
Notice that it's missing all it's iconic SLAs and then read the fluff. That's depressing, right there.
I noticed a mention of the Dark Eight in there. If the Blood War doesn't exist in 4e, and the Dark Eight were the ones that did all the planning for the Blood War, then I'm guessing the Dark Eight has a completely different role now.
Question. I thought that devils were supposed to be more human looking, and that was used as a justification for the succubus switch? I've now seen the pit fiend and the osyluth, and neither look very human.
Also, XP: 18,000? What, are they going back to how encounter XP was handled in 2e? Admittedly, I haven't been keeping up with 4e that much. I do like the exploding devil trick, though.
Aren't Pit Fiends supposing to be different color. (In 2ed they were greenish - I think).
Weishan is right: they have just 3 skills!!! Outsider levels at least had wider range of skills.
To be honest this is just Balor with mace.
EDIT:
Ornum wrote:
How do you feel about Irresistable Command from a fluff/thematic perspective?
Iressistable Command? Huh? Idea is OK, but it reminds me too much of World of Warcraft. (To order devil to go kamikaze).
But it is pretty much usles unless you wish to harras pessants or faceless troopers, and animal companions.
I mean it is uselles against demons (and devils) since it is fire damage (but there is not blood war anymore), and by the time PCs are raedy to face Pit Fiend it will be useless against them too.
Hey, if PC don't have deacent fire protection by the time they are facing Pit Fiend they deserve every bit of devil flesh blown in their faces.
(Then again I dont know much about 4e mechanics anyway).
Blowing up their own troops doesn't strike me as something Pit Fiends would do often enough to justify a special ability.
Also... Pit Fiends without any skills except Knowledge: Religion and senses ? WTF?
boo 
No worries there, all skills progress at 1 point per 2 levels. The ones that are specifically called out are the ones with a +5 bonus from specific training.
He's sunk if his foes all have high fire resistance, but that's supposed to be weaker in 4th Ed and much less available. I don't like it either, though.
My big beef is that he has no versitility. 3.x Pit Fiends could come at things all kinds of ways, what with their SLAs and all. It looks like this guy, OTOH, was built around a single specific tatic the designers wanted him to use.
Yes, but... the old pit fiend was too complex! .... Apparently... 
Dire Lemon Wrote:
Like all tied to Outer planes and its denizens. (they merge lower planes, elemental planes, and planes of chaos in single plane...)
Like they said in their own words: estimated average lifespan of monster in combat is 6 rounds. So it seems that is poitless for monster to have many special abilities if it won't use them.
So they have just decided to focus monster on thing they exist for (in their thinking): combat and XP storage.
Also it seem's that monster's abilities are tied now to class levels and not to monster levels, Pit Fiend in here example is Elite Soldier so his abilites are ties to combat not magic.
Well stats is all chinese to me, but as artist and old Planescape fan I cannot say that I like new Pit Fiend art very much. (They look just like Balors except they have mace instead whip and sword).
I mean even before TonyD they have drawn Pit Fiands as large stocky fiends with big bellies. Tony than added that iressistable iconic grin from ear to ear for compleate "Evil Santa" look.
And now they put poor Pit Fiend trough slim fast diet. Is it just me or they are trying to say that fat is "uncool". Yeech! :roll: :x
One-eyed, one-horned, flying, purple people eater says: "Monsters are nature's way for keeping XPs fresh."