You know I also think about ZigBee and hear about it simplicity.
But now the new version of ZigBee2 is comming and personaly I haven’t work in embedded design with ZigBee yet but with BlueCore yes.
At the beginning the CSR was look very difficult to uderstand because of poor documentations, but finally I managed and read all and found the way. Also I found one nice book about Bluetooth which has at chapter 7 very interesting information, even if it was for the first version on BlueCore and the old version of BlueLab, but some basics of BlueStack are the same. So this book also help me.
I also want to say that the new BlueCore has very low power consumption, so the ZigBee is now is not so far from it. I haven’t yet any benchmark for that, but I am sure that BlueCore6 and 7 are very smart even the one which I am using BlueCore4-External with 8Mbit Flash, which has Class 2 (10meter range) Wireless parts.
Also the very important thing comparing to ZigBee with Bluetooth is that the Bluetooth has many Profiles, like SPP, DUN, FAX, etc you can send a file and voice at quity higher data rate that ZigBee. And ofcause you can create even your profile if you want talking directly with RFCOMM, L2CAP layers or even to ACL layer.
And the key is that you can manage it with PC or even mobile phone with just simple Java (with JSR82 API) application. This is very important for me and very useful.
Also if you look in security side you can encrypt your transmition with 128bit at hardware level, without adding any software extra operation to encrypt more your data, ofcause if you need you can do it.
I dont know about the ZigBee security how strong it is.
But in any design with ZigBee you will also need to have a master design which will be connected to PC or maybe it will be independed, to conroll you slaves ZigBee.
Of cause some of the ZigBee advantages that you can support more that 7 nodes, up to 127. In bluetooth you need to manage this in different way, but even in bluetooth this is possible.
So to sum up I think in many thing bluetooth is more powerful and advances than ZigBee and concerning the simple control even by mobile phone this is very strong point for me.
But I am saying again that ZigBee is also good for some special cases, but for that cases it is also good to look and Cypress CyFi protocol which is very simple and very powerful.