In fairness to dojo, I think ExtJS is bordering along the lines of bloatedness but like dojo you get to mix n match and use only the libraries from the toolkit you need.
So what do I like about ExtJS so far;
- Choice. It started out as a project that extends YUI but it has now expanded to include jQuery and prototype.
- Widgets. The draggable treepanel and grid widgets are killer.
- Clean Object Oriented Code. Code can be easily extended or even overwritten if necessary. The uncompresed code is clean.
- Documentation. While incomplete the documentation and examples provided are clear.
- Themeing. I love being able to change the theme for all widgets .