I've been shooting a Lomo Diana+ for the past few years. A few weeks ago the winder broke and I bought a vintage Diana as a replacement. It gave me a chance to notice several differences between the cameras that I hadn't been aware of. Here they are, in increasing order of importance:
1. Strap is noticeably more flexible on the original.
2. Slightly different teal color. Slightly different lettering and distance notations.
3. Frame counter pane on the original is circular, brighter, and doesn't move to accommodate varying frame counts.
4. Spool holding mechanism on the original has levers which flip out for loading. Newer model has stationary plugs which bend. On both models this component is easily susceptible to breaking.
5. Lomo Diana+ can shift between 12 or 16 images, with pinhole capability. Frame size changes with insertion of plastic masks, and pinhole is achieved by removing the lens. Original Diana has fixed lens, fixed small frame. Since I never bother with pinhole or 12 frame masking, this difference is neglible.
6. Original model has a noticeably crisper shutter than the Diana+. It goes Ka-Chunk with a satisfying snap. The Lomo Diana+ shutter is very quiet and not very satisfying. I didn't realize how big of an issue this was until using a vintage Diana. All of the sudden the shutter feels as if something has happened.
7. Lomo Diana+ susceptible to bizarre flaring. This is different than a normal lightleak. When pointed at bright objects the image content can wash out in low-contrast haze. Frustrating, but I just chalked it up to normal toy camera unpredictability until using a vintage Diana. Flaring is completely gone now, though light leaks still turn up occasionally.
8. Images from the original model have more vignetting than Diana+, and the border is slightly rounder and cockeyed on the roll. They have more of a "toy camera" look, for better or for worse. Images from the Diana+ have distortion but are still fairly resolvable to the edges, which are straighter.
Center sharp, a bit of distortion on the edges, borders straight
Photograph from Vintage Diana:
Center sharp, blurry dark corners, rounded borders
This is really the most critical change since it alters the character of the photographs. I'm not sure why the lens was altered. Maybe Lomo couldn't track down any of the old plastic? In any case images from the newer model tend to feel a bit cleaner, more like a regular Canon or Nikon lens. Maybe sanitized is a better word? Whether one likes that look is open to personal preference. After using the vintage Diana, I'm starting to prefer its look but maybe that is because I'm conditioned by all the toy camera images I've seen.
I guess the upshot is that anyone considering buying a Diana should be aware that new and old models are not equally interchangeable.
(End of gear talk. Normal programming will now resume)