I should probably reply to this. Please note in my reply that I am very biased as I do work at the Dallas Zoo and know its goings on.
To answer the question about the neighborhood, yes it is not the most savory neighborhood to be had, but I have never felt unsafe at all being there, In fact I have a good friend who lives only a few blocks from the zoo.
Next point about the monorail being seasonal. This is in fact partly true. If it were a perfect world and the City of Dallas didn't have a $130 million short-fall, then yes we would run the monorail year round (except in extreme weather when the animals won't be out or it could potentially damage the train). The goal this last winter (officially at the zoo ended yesterday) was to have the train run every day, but a $2 million cut in the budget (which has incidentally happened not once, but twice in the past 4 months) didn't allow it. Instead we ran only on weekends.
No onto the big issue of Zoo North (misidentified as Zoo West). It has been known for a long time that parts of ZN are - how to put it nicely - an isore. But this only really encompasses TWO buildings. Unfortunately these buildings are some of the most visible Cat Row, that currently unoccupied due to construction but which normally houses ocelots, a bobcat, and fishing cats. This is the former home of our lions. The decision was made, and rightly so, not to house lions hear again and wait for the construction of the Savannah. I cannot tell you how many times I have to tell disappointed children at the zoo that we no longer have lions and that the only zebras that you can see are from the monorail. The other building is obviously the Large Mammal barn. I don't think I need to say anything here that has not already been said except - bring on the bulldozer!
Since the last posters visit several new or renovated exhibits have opened up in Zoo North.
Asian Small Clawed otters next to the tigers and in a similar style to the tiger habitat.
Winds of Wonder which is a redesigned area for birds of prey.
I'm not sure if primate place was open or not on your last visit, its not the most beautiful primate exhibit to be had, but I have definitely seen a lot worse.
A new Galapagos tortoise and Rhinoceros hornbill exhibit has opened (next door to each other).
Eventually, after the Savannah is complete (all of our attention is on that right now because of people like PETA jamming that fact down our throats) a renovation of Zoo North is planned as well as the updating of many parts of the Wilds of Africa.
Basically what it all boils down to is the fact that we are a city run organization and we have to abide by their rules as the hand out the money, and money has been so tight in the last few years that I am amazed that the savanna is even a reality. The current economic crisis has really hit the zoo hard, but we are trying to do the best with what we've got. It really should only be a matter of time before the Dallas Zoo can be called one of the best in the country.
And now I will step down off my soap-box and end my diatribe.