It's ok but not as good as the PC version. Fun for animal lovers!
The second thing I noticed is that you can't have multi species exhibits. That was part of the fun of Zoo Tycoon and it's real life zoo planning these days. You can't bulldoze fences and let the animals out to eat the visitors either (not part of real life zoo planning but great fun in the PC version). There's a bunch of other little things that were changed for reasons I don't understand (why a zookeeper in each exhibit for example. In the old one you could assign one keeper multiple exhibits. Guest and animal comments are not as detailed either). It probably has to do with the capacity of the DS but I've played other DS sim games and they're much better.
I haven't played long enough to see if the animal options are going to be as robust but they don't seem to be at the beginning.
Overall I think this was a badly designed copy. As long as they've been planning this game, you'd think they could do a better job.
I realize I'm a bit biased. Without the original to compare to, it's probably a good game.