I have said already that Keep on the Shadowfell is a bad module and I'm probably going to say it a bunch more before I am through.
When someone says, "this encounter is broken", or "this story element is weak", a common response on internet forums is, "Well, a good DM will modify it." Which is true. But not helpful.
A good DM could do any number of things. A good DM, one imagines, could run a perfectly decent game of D&D without reference to any printed material other than the Player's Handbook. Heck, a good DM may well not be running D&D at all.
A module is a product for which you pay money. And for that money you can expect to get something. If you are lucky enough to be a good DM, you are probably looking for something that saves you time by providing balanced, playtested encounters that deliver a fun experience for nine groups out of ten. If you're one of the great many DMs who are merely average, you're hoping for a dynamic, well-told story with lots of detail so you can run a fun session without having to stop every ten seconds to look up rules. You are exchanging your money for the writer's superior writing skills and development resources.
So when you find a module that appears to have been only patchily playtested, it is a bad module. When you find a module with encounters that could have come straight from a wandering monster table, it is a bad module. When the only friendly NPCs are cliches drafted into service from every fantasy pastiche ever, it is a bad module. There is no point in paying for something that you could have come up with yourself.
Keep on the Shadowfell has a bunch of small points of design brilliance, but they are spread out, and some are accidental. In between is a wide and deep ocean of the generic. Regardless of what you, or your friend, or someone you talked to on the internet may have done with it, it is - and will remain - a bad module.