I mean, the box cover says they are "carefully remastered for best possible picture quality" but they aren't Criterion transfers or anything, but they aren't bad either. There are also no commentaries and only a couple minimal extra features. I noticed on Sabotage the audio track had a slight low hum on it, but nothing that bad.
I personally have never seen any of these movies available as single DVDs other than the Criterion versions of 39 Steps and The Lady Vanishes which are out of print I believe.
I'd definitely recommend it. For real cheap you get 9 Hitchcock movies...that's hard to beat, even if they aren't his best.