The user interface is strikingly similar to Adobe Photoshop except for some icons and options.
If you are wondering what is Illustrator and vector based graphics, vector graphics is the technique which completely removes any kind of pixellation which is visible in pixels of most of the images we see[like jpeg, png, etc..]
In SVG[Scalable Vector Graphics] format, we get the same quality and clarity of the image, no matter which level of zoom you are in!So you can zoom in to 10000% and still find the sharp details just like they were at 100% or 25% zoom level!!
So, welcome to the "pixellation-less" world of vector 2D graphics!
Below is the simple svg image created by me!
The original SVG image is located here at Wikimedia Commons.
With love.. Anil