I'm pretty curious about the new features.
One thing I'm hoping for personally, is that it will now be possible to also have more on-line, low-latency types of interaction with BizTalk. I know we need to be asynchronous and loosely coupled, but this is simply not possible or the best solution for all scenarios.
Consider a user doing a lookup (based on a customer phone call) that needs some smart integration logic across multiple systems.
We have seen numerous cases were such functionality was needed. BizTalk 2004 is optimized for throughput, giving us a hard time to make low-latency scenario's work… and you don't want to switch do DIY because you would be missing out on transformation functionality etc…