Those are all the reasons I chose it in the first place.
But that last one wasn’t true for me (and for a lot of others too, according to their support forums), and so I went to another product.
OK. If you don’t mind, I’m going to pursue this a bit, both for my own edification and to address the following:
If avi is simply a container, is there a reason it would be ‘dead’? Or, re-phrased, what benefit does, say, mkv (or some other container) provide over avi (to such an extent that Handbrake developers would forsake it)?
Also, I was under the impression that MP4 is equivalent to MPEG-4 is equivalent to H.264 encoding. Is that right? Does ‘mp4’ carry with it certain connotations that may be different than H.264 and/or from, say, ‘m4v’? And so, your older DVD player that doesn’t recognize ‘mkv’ files also won’t recognize ‘mp4’ or ‘m4v’ files?
aceplace57, I suspect that the huge mkv files you’re seeing are either: (1) really high quality or (2) really badly done encodings.
It’s all there on the Handbrake website:
MKV also gives you additional features such as multiple audio tracks (for instance more than one language or a commentary track often found on DVDs) and multiple subtitles.
Well, that would require me to actually read the website. 
So perhaps that’s the explanation for the large mkv files.