It really doesn't look great in person. There are a few issues.
You can tell that they are being projected onto black curtains. It looks rather cheap. At least use something solid? You can see the curtains sway back and forth with the HHG projected on it.
It just looks TOO bright and TOO CGI. It just doesn't fit in with the rest of the mansion.
Also, part of the success of the previous HHG effect was that no one could figure out how it worked. There are no projectors, no AAs behind you or whatever, nothing. The effect was really well done, and yet if you know how it is done, it's so simple. Now, however, you can see the BIG HD projectors, and the light rays, shooting across the room.
I think it's so shocking as well because it's the climax of the ride, where you are supposed to see YOURSELF being haunted by a ghost, as per the narration. And now, with the scrim in the way, you just see the HHG floating along by, not even in sync with your doombuggy.
IF the projections were matched up with a 3D AA or surface, similar to Constance (the bride), and the mirrors were brought back, I could definitely see an overal upgrade and improvement! But for now, it's too shocking, and I see why most of us (who have seen it in person) are little upset.