Using Turbo HD is easy - helped along by my having had its lesser sibling for standard-definition content. The video file window is about twice the size of the one I’m used to but that makes sense I guess since high-definition is now part of the picture.

click to enlarge
In use, not much has changed. You drag in a file and watch it take form on the video window. Turbo handles a wide range, from Quicktime to AVI to DiVx to Video-TS files from DVDs. Or have it do YouTube in standard or HD resolutions or Sony's
PSP or just plain old good 720p or 1080p HD (too bad I don't have a Blu-ray burner and even more too bad that the Mac doesn't yet support BD). Plus now it also recognizes AVCHD camcorders that are attached to the Mac. The H.264 standard gives you a small but powerful file, easily viewed on an AppleTV or iPhone or iPod or whatever. Of course you’re picking from pre-sets for the most part - but it’s just as easy to create a custom setting (I ups the ante for AppleTV video all the time). Still it's not going to be perfect until it has a subtitle section for switching between English and other languages.
Now when it's done, Turbo signals you and transfers the converted video to iTunes for use. Of course you can have it transferred somewhere else if you'd rather - one good thing is that unlike some software converters I used to use, there is no copy being made along with the file being transferred to iTunes. So that eliminates having another file to delete afterwards.
Now those with slower machines will find Turbo even more an effective means of converting video without having to baby the process along.