I've been deploying CRM 3.0 in several enterprise environments for a couple months now, and I like it. Even the CRM 4.0 ("Titan") bits I have been playing with are pretty cool from a developer's perspective.   You will enjoy working with CRM as a developer!

The cool stuff we have been doing is aggregating several backend systems to integrate data into CRM, and exposing that (through custom UIs throughout the enterprise) using custom Web Services. We have done this leveraging the Web Service Software Factory (see CodePlex). We took to architecting mappers and accessors for schema-mapping our business objects with FetchXML calls from the data layer. It's actually pretty fun to see all the nuts and bolts come together.   I've also been writing custom SSRS reports against the filtered views, which is interesting to get around issues here and there. ("Table variables are our friends...")

I'm enjoying CRM because you need a bit of ActiveDirectory/IIS/Exchange/Kerberos experience intertwined with SQL/.NET WS dev skills and you cross product lines a bit more than normal (SQL Server 2005/Windows Server 2003/SharePoint Server 2007/Exchange Server 2003/BizTalk 2006).

Becoming a "CRM Developer" is no trivial task IMHO.. you need exposure to other facets of the Microsoft stack to be a tried and true CRM Developer at the enterprise level.   A great place to start is the SDK, but for all the intracacies involved, your skills will surely be continuously challenged and rewarded.  Cool