The following is a series of posts I made on my old blog regarding control suites. I think it should be an interesting read for anyone evaluating a 3rd party control suite.  Be sure to read both posts.

March 31st, 2006
The Honeymoon Is Over: My Farewell to 3rd Party Controls

Over the last couple of years I have used web controls suite from Infragistics and Telerik. I was a very enthusiastic user, and I think that I could have been a product evangelistic for Telerik about 9 months ago. Telerik seems to have an especially agressive development cycle and they deliver new products every couple of months.

So what happened?
Well, the whiz-bang wore off and I began to realize the following deficits:

• Inadequate Documentation. 3rd party never seem to be documented well. Sure, there's lot of documentation for both Infragistrics and Telerik, but that doesn't mean it's good documentation. I can't come down on them too hard. My wife is a tech writer and I understand the difficulties of writing good documentation. However, I can never seem to find what I need. Which leads to the next problem...
• Inconsistent API's. I personally try to follow Microsoft's guidlines and examples. I want a .NET developer reviewing my code to feel "at home", like my code is a natural part of the framework itself. Now, I understand that 3rd parties may have excellent reasons for establishing their own feel. However, both API's are inconsistent even within themselves. Don't expect methods that do the same thing on different controls to have the same name. I feel like I have to become an expert with each and every control.
• Bulk. Too many features. Does that sound backwards? I spend a lot of my time figuring out how to minimize what the control does. Take Telerik's rich text editor; it rivals Word. Additionally, the acutal HTML rendered for many of these controls is expansive. I've ended up writing a number of simple controls,with simple output just because using a 3rd party control seemed excessive.

I will say a positive thing about 3rd party controls. If you have a relativity simple application to development, and you want very rich client functionality, these suites will benefit you. However, if you are writing commericial applications for a wide audience, and if performance is an issue, then I would recommend being a bit more wary.

April 9th, 2006
Telerik Responds

I was surprised and somewhat humbled last week to receive an email from the CEO of Telerik, Vassil Terziev. He had come across my blog post where I criticize 3rd party control suites and wanted to respond.
To summarize, he was very cordial and acknowledged each of my complaints as valid. He explained that Telerik has recently changed a few things about their development cycle in order to improve upon the weaknesses I listed. He also pointed out a few things Telerik has already accomplished to those ends (such as a 70% reduction in output from their tabstrip product).
His email was personal, friendly, and transparent about his products. I was very impressed and the fact that Telerik has that kind of leadership encourages me to give their products another chance.
Luckily, my employer's subscription to their control suite still has many months left. Expect me to post my reflections upon the updated Telerik products when they arrive.

September 20th, 2006 

I never did get around to really evaluating the improvements that Vassil listed.  We did continue to use there controls and I have continued to be impressed  with their attention to customer input.  I have had some performance issues with the rich text editor, though mostly in an environment with multiple instances of the editor on a single page.