nServiceBus does a great job by hiding the complexity of the management of messaging in an application : transactions, durability, reliability etc. We can think it’s simple but it’s not. What it’s easy is the setup of nServiceBus: some configuration file, writing a message handler and you are done. I like the idea that you can focus on your business as developer: writing code for your application not the infrastructure. Coming from the J2EE “world”, nServiceBus reminds me a lot JMS with annotations.
nServiceBus is used by a web application to handle registration confirmation, notifications, statistic gathering .We have a lot interactions with Twitter, Facebook or by email and be able to have messages hold on an error queue when theses external systems are down and resubmit them later without any difficulty was very attractive.
I think that there’s room for improvements for the documentation but the user group is great (even if it’s not simple to search the yahoo archive …) and you can get an answer very fast.