I've gotten used to using split image and find it much superior to just a plain matte screen. The images I took with a Zenit E (which had ONLY a matte surface) came out sometimes quite out of focus. I've stopped using my Retina started using more modern cameras like Minoltas, and they all have split image, sometimes with 3 split images in the center or with the image tilted, and all are a small improvements.
However the lack of a microprism collar on the retina is a bit of a shortcoming, but not that much, since you can used the ground glass surface of the rest of the screen, but it seems like the microprism/acute matte field came to be standard in later cameras.
Interestingly, I have a Kiev 6c with ONLY a microprism center-spot focusing aid. I will see how this works. The later Kiev 60 has a microprism collar with split screen center, so it was an "upgrade". But I like the microprism mechanic, which shows a "shimmering" image if the image is out of focus, but which does not function well on small and darkly-colored objects.