My 2 cents (Oculus Go user):

Preface: Skybox is a very nice program. I wouldn't know what to do with the Oulus Go without it.
Minor bug: I converted a DVD into a single vob file with the the "vob (pass-through)" preset of SetupCloneDVDmobile1950. VLC on the PC could play the file normally and seek in it. Skybox could play the file sequentially but the timeline was wrong. Total movie length was displayed as 3 minutes or so and Skybox couldn't seek in the file. Seeking would restart playback at a much earlier time. It alsmost seems as if VOB files are made up of short chunks and Skybox looses the orientation which is the current chunk.
Granularity: I love the contrast and brightness settings of Skybox, they greatly improve the viewing experience. But they are a bit too granular. For example, in many cases, contrast 0 is not enough contrast but the next step is already much too much contrast. Several settings in Skybox seem to lack granularity. Contrast, size etc.: These could be a bit smoother by offering many more steps in the respective sliders. Not just 5 arbitary steps or so. It's not as if they cost money.
Gamma: Having a contrast setting is great but gamma would be even greater.
Networked files: The automatic generation of thumbnails for files on a networked drive doesn't look like the best idea. It slows everything down if hundreds of video files are briefly opened. The file explorer really needs an option to turn those annoying thumbails off (like most exporers). Caching images is also a privacy issue.
Transparent user interface elements: I wonder if the overlays could be made semi-transparent? It limits usefulness of A-B-repeat etc. a bit if the video is mostly obsured by dialogs and other elements while using these functions.
Scrolling in the settings dialog: It's very hard to avoid hitting sliders while drag-scrolling through that dialog. It could be a bit wider to make drag-scrolling easier. Sometimes, a dragging operation in that dialog somehow moves that dialog. Afterwards the dialog is in a oddly rotated position.
A-B-Repeat: The A-B-repeat apparently can only begin on key frames. Would it be possible to let it begin anywhere (i.e. decode the frames between key frame and the user's desired A point as fast as possile without displaying anything)?
Orientation of movie: It seems as if moving the 2D image in the virtual cinema with the pointer can only move it in a sphere-like fashion: If you move it left or right, it gets rotated, too. It's not possible to just move it left or right. The only way to do that is to move the head and reset the view. That seems weird.
Touchpad issue: Horizontal movements on the Go's touchpad (seek opertation) are picked up perfectly but vertical movements (zoom) very often are ignored and require a few attempts. The controller's touchpad could be defective but I suspect a software issue.
Virtual keyboard: Something is wrong with the virtual keyboard used to enter user name and passwords for networked files. It just doesn't pick up some clicks. I don't have that problem with the virtual keyboards in other apps. It seems this is a self-programmed component and not a system component? I suspect that minimal pointer movements between click and release are enough to drop characters. If that's the case, it should allow more movements (accept all clicks that begin and end over the same character?). It could also provide better feedback (flash the character).