Broad question is: Is there anything Telerik Reporting can do that SSRS (2005) cannot?
Specifics: We\'re looking to migrate our current Reporting infrastructure from in-
Just adding to mika's reply regarding Telerik interactivity:
Their reporting now offers a few interactivity features, namely navigating to a subreport (drill-through), navigate to a bookmark, and navigate to URL. Their current roadmap mentions that they will add interactive sorting and drill-down by the end of 2011. These should bring their reporting product much closer to SSRS in this regard.
In the latest versions Telerik Reporting have Report Designer that is tool like Report Builder and the report viewer support XML report definitions (trdx). So no compiling is required if you change the reports.
One of the main reasons we stopped using SSRS and went with Telerik is because Telerik has much better support across browsers. Naturally, one would not expect MS to provide equal support for a rival product when it comes to browser compatibility. Since you are planning one doing a web based application this may be a factor.
I first started using Telerik reporting version 2010 Q2 and never had an issue linking reports over a web app to provide drill-down or linking functionality. It was quite simple and intuitive.
Another thing to think about is that SSRS report files which are RDL files, whereas a Telerik report is compiled into your app. If you need to change your report you'll need to recompile and redeploy your app. For RDL files, you simply upload them to the SSRS server. I still prefer Telerik though, even though it means a slightly longer SDLC for a change request.
Another thing that grinds my noodle is that as long as we used SSRS we had to have both VS 2008 and 2010 installed, because VS 2010 does not have support for designing RDL reports like 2008 has (BIDS is basically a scaled down version of VS 2008: Visual Studio 2010 Reporting Services Projects? )
With Telerik we can stick to using VS 2010.
Comment on "Telerik Reporting has excellent support too. Developing Telerik reports relies heavily on samples and support forums.": No. You're making an assumption. I have created many complex reports without needing any direction from forums/sample/etc - its a very intuitive tool. I am sure there are many developers out there who have been able to do just fine without "heavy" reliance on the forums/samples - its not rocket science, it's cake.
SSRS is a server-based reporting system whereas Telerik Reporting is purely an embedded reporting tool. You should compare Telerik Reporting to SSRS ReportViewer control in local processing mode, not the whole SSRS system, unless you intend to use the SSRS server too. I think this is the first question to answer: you should evaluate the pros and cons of using a report server.
The usual reason of choosing embedded reporting is to avoid a server dependency. If you are an application developer and deploy your application to multiple sites, you would have to support multiple SSRS installation in addition to your application. Telerik reports compile to a dll that you can deploy with your application easily.
Generally, server-based SSRS is more feature-rich than Telerik reporting, especially the SSRS 2008 tablix is handy. I think that Telerik Reporting has supported crosstabs only from Q1 2009. It does not support interactive features like drilldown. You should see the known limitations of Telerik reporting and also the substantial improvements in SSRS 2008 compared to SSRS 2005. On the other hand, ReportViewer in local mode understands RDL 2005 only, so you are limited to SSRS 2005 features.
Now, it is easier to look at your requirements.
Generating reports from a custom ASP.NET application
Scheduling reports
Email reports on demand or on a schedule
Pdf output
Drilldown html
Massage the dataset in C# before passing it to the rendering engine
ReportViewer supports two types of data sources in local processing mode: a dataset that contains an ADO.NET DataTable object or an enumerable collection of business objects. ReportViewer Windows Forms also supports binding to instances of System.Windows.Forms.BindingSource and to System.Type. Report Viewer Web server supports binding to an instance of System.Web.UI.IDataSource.
Given your key elements, and assuming that you are doing internal reporting inside a corporate firewall, I'd definitely recommend using an SSRS server. Try to get one SQL Server 2008 licence or use SQL 2008 Express as a reporting server. But if you absolutely have to use embedded reporting, Telerik is probably a better choice, at least until Microsoft ReportViewer supports RDL 2008 in local mode. This new ReportViewer should be shipped with Visual Studio 2010.
For SSRS, I recommend reading Teo Lachev's Applied Microsoft SQL Server Reporting Services. Sample chapters are available at the book's site the and in Google Books.
Telerik Reporting has excellent support too. Developing Telerik reports relies heavily on samples and support forums.
I have also written blog posts on embedded reporting and Telerik Reporting in particular.
I want to add some new information about Telerik's solution.
Some of the things that were previously not supported, such as Scheduling reports and Email reports on demand or on a schedule are now available as part of the Telerik Report Server product. The Report Server comes with the Report Designer mentioned above. More information about if is available here.
SSRS Local mode is not supported in Azure.