I received my Gemini 4G from Planet Computers in the first week of May, so I've had about six weeks of daily use and can now offer my observations and opinions.
I'll begin with a summary of what I was hoping for when I decided to hand over my money. Because it was promoted as a dual-boot Android and Linux machine and its hardware specs looked decent I planned to use it to replace my aging laptop machine; the Gemini would become my primary computing device. Its portability would allow me to have my computer always with me, which wasn't practical with the laptop. I expected I'd spend 90% or more of my time in Linux.
The overall quality of the machine is good. The screen is bright enough to be usable outdoors in summer sun. The keyboard is the best I've used on a device in the palm-top size range. It is portable -- it rides around in my pocket wherever I go. It is powerful enough for (almost) all of my routine computing tasks. I've never come close to finding the limit of its battery because when I'm home or at the office it is always plugged in to a charger. When it comes to outdoor use, or work in the field, the battery's endurance is greater than mine.
The machine did not arrive with a working copy of Linux pre-installed. I've been following the progress of the Gemian team but have so far not mustered enough courage to risk a do-it-yourself install of Debian. Though I've got years of experience as a Linux system administrator I have zero experience with Android machines. Plus, I've invested enough time into configuring and customizing my Android install by now that I'm very reluctant have to do it all again following a Linux install.
The video-out support is limited: I can't extend my desktop, only mirror it. The only HDMI output option is "Auto" so unless the monitor or projector offers direct support of 2160x1080 there is either no display at all, or (sometimes substantial) portions of the display are clipped from the left and right edges. I've had spotty results connecting directly to TVs using the HDMI adapter, but reliable connections using an HDMI->VGA adapter.
The e-mail client that had been my favorite for Android (K-9) is almost useless with mouse and keyboard. While reading a message the space-bar doesn't scroll the display, nor the scroll-wheel on the mouse -- I can use a click-and-drag to scroll, if the click doesn't activate a link in the body of the message. And why isn't there an option for text-only display of messages? HTML doesn't belong in e-mail. I'm still testing replacements -- maybe I'd better get involved in the K-9 project instead and work for the changes I'd like to see.
The (built-in front facing) camera is all but useless to me, since I don't do video conferencing or selfies. It is very difficult to see the screen well enough to frame your image and activate the on-screen shutter release without including one or more of my body parts in the resulting image. I've ordered the add-on rear camera.
The machine is not effective as a cell phone -- you know, that old-fashioned wireless device that enabled one to make audio connections with others (SMS, MMS, and other smartphone features have never been important to me). Even with the "Answer call in speakerphone mode" setting enabled I find that answering a call is awkward and prone to failure. Placing outbound calls has been more successful, but the only time I use the Gemini as a telephone is when it is the only option available to me at the time. A Bluetooth headset helps immensely, but I don't like to wear one constantly.
I'm still hitting "m" instead of "," on this keyboard. I think it is because I'm seeing the Fn-M indicator for " ' " (apostrophe) on the "M" key and I don't expect the "," to be one row down next to the space bar. It is a small keyboard; I will get used to it eventually.
Some Gemini owners have reported that the upper half of the machine wobbles or flops back and forth annoyingly during handheld use, while others say that the hinge (or perhaps the spring) is tight enough that the screen is solid and stable while not on a hard surface. Mine is definitely more loose than I desire.
It doesn't handle large-ish files well. I suspect that having more RAM would go far toward resolving this issue. I needed some data that I downloaded from a local government website: a shapefile (geospatial data for mapping) about 80 MB, with a little over 61,000 records. I couldn't find an Android app that would handle that map data in a useful way, but I did find an app that would extract the tabular (non-spatial) data to a CSV file. Unfortunately, none of the apps would handle a 24 MB CSV file either. Back to my desktop machine to pull the shapefile into a Sqlite database, then load the 50 MB database on my Gemini. The aSQLiteManager app handles this file with no problem, and I was able to extract the 40,000 records that I really needed into an HTML table. Alas! none of the browsers I've tried nor any of the editors -- except the text-only versions running inside Termux -- would handle the resulting 5 MB HTML file. Trying again, I had aSQLiteManager export the data as CSV, which was only 3.3 MB -- success! AndrOpen Office can actually open and use the file. Now, where I come from, none of these are considered to be large files, but the Gemini running Android certainly chokes on them (and yes, the files are valid and work on the desktop and laptop machines I've tested them with).
Please give me an option to easily toggle touchscreen input off and back on again. Especially when using the keyboard in handheld position rather than on a table top, I often bump the display with one or another of my fingers -- with unpredictable results as to where the cursor will end up or which app or function inadvertently gets activated. My laptop had an option to automatically and temporarily disable the touchpad while I was actively typing on the keyboard, that's what I need for the the touch-screen.
External volume-up and volume-down switches would be immensely useful, especially since a number of apps make effective use of them beyond controlling audio volume. It could be useful to map them to zoom in/out for the camera app, with the current silver button as the shutter release.
At first I tried using a case with a belt clip to carry my Gemini around, when I still imagined that it might replace my much smaller flip-phone that still rides on my belt. The case really didn't suit my needs and I discovered that it was just more convenient to keep the Gemini in my shirt pocket.
The HDMI adapter has been a source of frustration even beyond the already-described single resolution output. It just doesn't connect reliably, I have to fiddle with the adapter to get a working connection and sometimes I give up before I accomplish my goal. I suspected a defect in the USB-C end of the adapter; Planet provided a replacement adapter, but I have exactly the same issues with the new one. I can only get a reliable connection using Gemini -> HDMI adapter -> VGA adapter -> TV or monitor. It may be quirks associated with the particular TVs I'm using, but it is frustrating nonetheless.
I've already mentioned some of the drawbacks with trying to type on a hand-held Gemini. It works best when placed on a table or desk or some other flat surface. I've come up with an adaptation that makes it easier to work when I'm sitting in my rocking chair or on a couch or in other less-than-ideal positions. I found a serving tray (about 18x13x2 inches) in the housewares section of the local mega-retailer, turned it upside down, and glued a mouse-pad to the back side in one corner. Though my Bluetooth mouse works without the mouse-pad, it works better with it. The inverted tray sits quite nicely in my lap or on the bed next to me. It is a different perspective on the term "computing platform". The tray makes a good way to carry my reading glasses, mouse, and other accessories from one place to another -- or we even actually use it a serving tray if the occasion demands.