Vegas is a high-end tool that's been made more accessible to users on the low end. It doesn't make as many concessions toward nontechnical users as some of the other programs here, but its learning curve is not so severe that newcomers will be totally lost. It's a program that you can grow into over time, and the amount of power you get for the price is remarkable.
Sony Vegas Movie Studio HD Platinum 10.0 is a pro-level product with some concessions toward less-technical users, but the learning curve is offset greatly by the interactive tutorial function.
From the outset, the program strongly resembles other professional level products, like Adobe Premiere. The timeline at the bottom automatically presents several pre-labeled, commonly used types of tracks: text, video overlay, main video, voice-over, music and sound effects.
At the top are various dockable panels: Project Explorer (which includes media for the project, but also has tabs for transitions and video effects), Audio Mixer, Clip Explorer (for viewing and editing individual clips) and Preview Window. If you have multiple monitors, the preview window can be dedicated to an entire display of its own.
Vegas helps beginning users with its interactive tutorials, which cover a great deal of the program's functionality in a succinct and easy to digest manner. The tutorials interact directly with the program itself, so you work in real time with the functions they're talking about, in other words, you can call up a tutorial on a given aspect of the program and apply it directly to what you're working on. This goes a fair distance toward making up for the lack of things like automated content creation tools.
You also get a lot of stock audio content, more than 300 clips of varying lengths and styles, which helps make content creation that much easier.
A number of Vegas' features make it a little easier for users who are new to video editing. If you overlap two clips on the timeline, the program assumes you're cross-fading between them and automatically creates that transition. This automatic cross-fading behaviour can be turned off if you don't want it, but it's a timesaver. Changing the transition type is as easy as right-clicking on the default transition and selecting a new transition from a list. Double-clicking an edited transition shows you its properties.
Like Adobe Premiere, Vegas has its own image stabilisation plug-in, which zooms in a good deal more than Adobe's own feature. It's not a problem with slightly jittery videos, but if you've got a very shaky shot, you can end up with footage that's too zoomed-in to be useful. Use it with care.
Vegas Movie Studio exists in a couple of different incarnations, depending on your needs. The Consumer edition leaves out the DVD authoring, image stabilization and colour-correction/chroma-key tools (among others), while the Production Suite edition adds many sound effects and audio tools.
Above them all is Vegas Pro 10, which includes many advanced features such as editing and compositing 3D footage, native support for many high-end digital video cameras (like the Red One) and support for gigapixel images.
There are a couple of things missing that would have made the program more accessible to less-video-savvy users, such as a storyboard-style editing mode, which is included in Corel Video Studio Pro. But on the whole, Vegas is a pro-level product whose learning curve is offset greatly by its interactive tutorial function.