Map panel 28 is not as big room wise as some of the others, only adding 17 new rooms to the count however it will provide some interesting rooms to play with for dungeon masters and adventuring parties. Groups by now start figuring out this could go on forever and that is the idea of the underdark, nothing predictable and never sure if the next area is the last or just the start of another series of rooms. I think this is one of the fun parts of the underdark is the unknowing of what could be ahead and your range of vision is merely the next turn of the passage. Anything could be just down the next turn or room, from a dragon eating a meal or orcs looking for a meal, you never know until you take the turn.