My opinion of DDLC has waned over the years, as I've played through it enough to see it as only just barely hitting the mark of a well-executed psychological horror game. But I think, with the extra side stories included within this "expansion", I am able to appreciate it a lot more.
The greatest part of this game was always the characters. They were well designed and have some great interactions together.
My biggest gripe with the main game was that it ends up focusing on the "breaking the fourth wall" haunted game surprise concept a lot more than the actual characters. This is certainly what Dan Salvato was going for (he says as much in the end note), but I couldn't help but feel that Doki's strongest aspect was not the horror, but the dark reality of the character's hidden mental states and secrets. This is EXACTLY what the side stories focus on and I couldn't be happier. They focus on relationships between the four characters. No computer glitches or creepy text, just raw visual novel story with emotions flying high.
I feel that everything about this part just works. The writing is beautifully done, the visuals continue to compliment the story and the new soundtrack was a delight to hear. I was extremely touched by these chapters.
Unfortunately for me, it's very likely that any future DDLC games will be related to the other aspect of this world, being that DDLC is a simulation created by some unknown organization. I can only assume the focus will be on this fictional world housing DDLC's fictional world, which is a bit disappointing for me. Still, I did like the improvements made to the menu, with the new desktop making it much easier to open and close the game, as well as being an efficient way to keep track of which scenes you have and haven't seen.
Whether or not you'll enjoy DDLC+ really depends on how much you like psychological horror, but are also willing to sit in for some really good and emotional VN fun (or the other way around).