Can't speak from experience (yet) but
@pkrieger2287 and Amy's video review implies they find the Deluxe Studio quite spacious. I actually think the "loveseat" is quite nice and fits well with the mid-century modern vibe. Not sure how I feel about the lack of a table to perhaps eat at, but I think overall the furnishings and quality seem up to standard with recent DVCs...I personally prefer the style over Riviera (but I live in Europe now, so I'm likely a bit jaded on the "faux Europe" vibe). I think the table at Riviera clutters the room a bit (and it seems there is plenty of space to add a similar sized table in the VDH space in front of the loveseat). Keep in mind VDH also gains the "desk" area (and two ottomans) at the built in, which Riviera doesn't have.
It also looks like there is plenty of storage space in a Deluxe Studio - 6 full drawers in console plus another cabinet with two shelves, closet seems plenty large (although Rivera does win here with a larger closet) and the ottoman/coffee table is also storage. Keep in mind that stays tend to be much shorter at the CA resort compared to FL so I think what they've provided is more than adequate. I actually think it's more storage than a Riviera Deluxe Studio given what you lose at Riviera to get the 5th murphy bed under the TV.
Riviera definitely wins on the bathroom setup, but I don't find VDH too bad. I can't speak to the Duo Studio/Tower Studio comparison as I've not stayed in that type of room before....
As to value, of course it's in the eye of the beholder. I also struggle with the "value" at VDH given where the
point charts landed, lower points requirement at VGC and the addition of the TOT. It won't be somewhere we stay regularly (we'll stalk VGC availability if we want to visit CA and will likely just try VDH for a check the box exercise) - but to be honest, I can say the same about Riviera despite it not having TOT...too much better value elsewhere at WDW DVCs.