I have not installed it yet, and I'm usually reluctant on installing plug-ins for VS because when they work, they work, when they don't, they really screw your system.
On the case of SlickEdit Gadgets there is at least one thing that I would love to have: Indentation Guides. Those that are familiar with Photoshop know how useful Guidelines are to make sure things align properly. I never thought of that on the context of a language editor, but it makes a lot of sense.
When you have just 2-3 scopes of identation you can easily visualize where things starts and end, but when you have 4-6 then you can't. I'm a big advocate of clean code. Having a 8-level deep scope is unacceptable. However, on HTML and XML that is mostly not an option, like it is in C#.
I'll try and let you know if I love it or hate it.