I've been converting Crystal Report v.10 to SSRS 2005. For the most part its been seamless.
Take the existing Stored Procedure plug it in, add a table to the report and fill in the fields, maybe add a few groups.
But the one thing I've noticed is Crystal Reports handles Sum's a lot easier than SSRS. For example, trying to sum up the Grouping are not straight forward and require a lot of hoops. I found that modifying the Stored Procedure to do the heavy calculations is the way to go. When the calc'd values get to the report, summing them up is fairly straight forward. That's what a lot of the newsgroups said as well.
I like Microsoft's implementation of SSRS and I really like 2008 version.
Although I have 15 years of creating report in Crystal Reports, and 2 years experience with Actuate, I've been converted to Microsoft SSRS as my reporting tool of choice.
Then add in SSIS and SSAS and it's definitely got its foot in the BI marketplace.
I will get a chance to develop some OBIEE (Oracle Business Intelligence Enterprise Edition) at my day job. Can't wait to see the pros / cons of that tool.
Although reporting was once the step-child of the IT world, in the end, it has finally caught up.
It's all good.