The ASP.NET AJAX framework comes with a lot of baggage err... I mean... a huge learning curve when compared to other AJAX Frameworks like JQuery, YUI, Dojo, Prototype / Scriptaculous.

Here's a running list of the technologies, and concepts you'll encounter when digging into ASP.NET AJAX:

• ASP.NET
• The Page Life Cycle
• The Control Life Cycle
• Web Controls
• User Controls
• View State
• Session State
• Events
  
• .NET / Classical Language
  
• Interfaces
• Inheritance
• Delegates
• Multicast Delegates
• Assemblies
• Properties (Get / Set)
• Constructors

In addition to these, you also have the technologies universal to all JavaScript libraries:

• JavaScript:
• Closures
• Object Literals
• JSON
• Events
• DOM Manipulation
• Prototypical Inheritance
• Constructors
• XMLHttpRequest
  
• Cascading Style Sheets (CSS):
• Web Services

The ASP.NET AJAX Framework is more complex than other AJAX frameworks, I'm continually lost in it's ambiguity as it attempts to skirt around the JavaScript language - I think this learning curve (and all it's confusion) is precisely why Silverlight has so much potential.

I'm still diving into the low-level details, but my first impressions of the ASP.NET AJAX Framework are:

• Obscure, ambiguous, no clear vision - it offers multiple (resource intensive) ways to avoid writing JavaScript, but then requires that you write JavaScript anyways
  
• Too server centric
• Too heavy weight (I'm not appreciating how they're trying to turning JavaScript into a Java, C#, .NET clone, the overhead within the browser for these conversions seems like a huge performance bottleneck)
• Has the potential for poor performance

Most of the other AJAX libraries have been written with performance, browser responsiveness, and User Experience as their number one priorities - I'm still not sure about ASP.NET AJAX.

How many ways can we try to avoid writing JavaScript? If an AJAX library doesn't enhance the User Experience then why use it? Regardless, I'm still digging deeper.