It's a translated version of Clip Studio. And I've tried clip studio with the fan made english translation.
What I don't like about Manga Studio (from the old days) is that it takes to long to upgrade (if ever). Clip Studio is far supperiour to tools like SAI, and I liked it much better than comic studio (Manga Studio 4), so it's worth it if you like those tools.
I just bought MS5 (I have MS4 EX). Really like the overhaul of the interface for the most part and the coloring capabilities, however, unless I'm doing something wrong--I like out-of-the-box the brush response in MS4EX better. Plus they left out some of the EX brushes I like in MS5 (along with some other features).
MS should let you change the sequence or order of the panels in a page by simply changing the order of the panel folders in the layers pallet. For example, if I want the images in panel 2 (in a split panel ruler 2 horizontal, 3 vertical layout) to be in panel one and the images in panel 1 to be in panel 2, I should simply highlight the panel 2 folder and drag it above panel 1 folder. Further, I want the images in panel three to be in panel 5, i move the panel 3 folder below panel 4 and panel 5 folder below panel two. The panel folder sequencing numerals should automatically change when I do that [from 2 to one and 1 to two, and 3 to 5 and 5 to 3]. When MS can do that, I'll be impressed.
Oh man, at first I thought they were just replacing both debut and ex with a regular fully featured version, but I see it was just too good to be true! I think that I'll stick with EX4 for now; though some of the features of 5 look pretty smashing.
I also purchased the Japanese version (CLIP Studio Paint Pro) and have been using it for quite a while. It is the best drawing/painting program I have ever encountered on a Mac.
I'd say this is more of a competitor to Photoshop than SAI. SAI doesn't have the power that CLIP Studio Paint or Photoshop has. If you were to move on from SAI to Manga Studio, there's gonna be some getting used to, but it'll be easier than moving onto Photoshop right away (The lines are smooth and the brush engine is very intuitive).
I bought the Japanese version for the sake of constant updates. Smith Micro is not very good with updates. (That and I find it hilarious that the cover art was made with Painter. I could understand Manga Studio 4's cover since you can't really make something like that with it, but with Manga Studio 5, you have all the tools you need to make a illustration look like that since it's a painting program now.)