Real project biztalk tasks.

Hi,

Im in IT for nearly 4 years now and have worked on a lot of dev projects, my core competency is sql server,IIS, asp.net, webservices and C# . I thought of learning biztalk server on my own and I found that it was not as diff as i initially thought, but most of the samples and examples i find online are rather naive. Could anyone point me to some kind of real life biztalk integration experiences??  I mean is it typically like taking flat files from mainframes through ftp and updating a sql db for custom web apps to read it..now that sounds very simple and easy. What I want to know is what are the typcial challenges that are faced by a biztalk implementation, also what are the tasks that a biztalk developer has to go about doing in a new biztalk implementation???

Real life scenarios will be highly appreciated.

Thanks,

Mahesh