Well, I was a long ZT1 fan and finally I decided to give ZT2 a go... I just played through the tutorial, 1 challenge and toyed a bit in freeform.
Here are my first impressions:
1) I like the 1 person perspective, its usefull when planning an exhibit, plus it allows you to clean that one little poop in the middle of an iceberg (man, I hated that in ZT1 the couldn't get to trash or poop beyond water)
2) The challenges seem cool for now, although I heard that they are buggy, luckly I didn't expirience it yet.
3) FINALLY no inbreeding! I still remember when in ZT1 I bought just 1 female an 1 male aardwolf and in a year I was reciving messages like : "Aardwolf 56 doesn't like its exhibit..."
4) The major cons of ZT2 is the low amount of animal species and seeing how its much more difficult to make custom ones than in ZT1 the hings are not looking well...
5) The enviroment suitability and similar stats are not shown in percentages, for me this is a big minus. Colorfull graphs are nice if you want to have a quick check if all animals are OK, but when looking at animals in-depth I'd like to have numbers!
6) I found one weird bug: I made a Mus Ox exhibit where one of its sides was the main Zoo wall. The exhibit was fine, but after a month or two I noticed that one Musk Ox escaped the exhibit and was standing on the road outside of the Zoo itself!
The fence of the exhibit was not damaged and the zoo entrance was too far away for this Musk Ox to use it. The only explanation is that the Musk Ox somehow managed to jump through the main Zoo wall... I could understand Monkeys climbing it, I could even understand a Panther jumping over it... but a Musk Ox?!
All in alll the game looks better then I had expected but before there will be more animals available, I will still consider ZT1 the better game of the two.