Thanks for putting this extensive review together. I think it will do a great service for the community and for the open source hardware movement in general! I like how it is written and the extra care of putting a website together to guide people!!

Here are comments I hope serve to make the review even better:

Minor:

1- In the PDF version I got, some underlined words (which I am assuming were supposed to be links), are not working as links (or are at least formatted differently from other links). Could you please review?

Line 89 – raspberrypi.org
line 140 – same
line 354 – Orcasound.net
line 374 – growcab
line 408 – makerbeam.com
line 426 – raspberrypi.org/downloads/
line 448 – github.com/brockgr/csshx
line 457 – remote.it, ngrok, dataplicity
line 577 – auto-scope
line 610 – motion-project.github.io
line 613 – PiKrellCam, elinux.org/Rpi-Cam-Web-Interface
line 639 – dexterindustries.com/grovepi/ (although there is another issue with this link, see below)
line 671 – pyimagesearch.com
line 688 – rclone.org
line 716 – stackexchange, raspberrypi.org/forums/
line 737 – school of lights

2 – on line 65 the author states that the RPI is “by far the most popular single board computer...” but there is no hard evidence for this, beyond the number of units sold (as advertised by the Raspberry Pi foundation). If possible could you add more data to this? How are the other SBCs doing? Maybe there are some of these that are sold I, say, Asia that sold more units than the RPi? Maybe a better measurement of popularity is the number of users/forums/languages for the documentation? Or even the number of addons (HATs, etc) for it?

3 – Line 107 states that the RPi can “be used as a headless remotely controlled unit”. I think for readers that are not familiar with programming, this is not going to be clear. Please add 1-2 words about what headless means?

4 – this is more of a general comment/question: on lines 118-120 what is described as advantages of SBCs, are also tasks that I can do cheaply (and maybe even an order of magnitude cheaper) with microprocessors. Are there more striking reasons on why to use an SBC for them? Maybe adding a few lines when RPi is compared to microcontrollers on how programming the same tasks in microcontrollers is harder than on Pi due to memory/storage/processing power constraints would help make this point clearer?

5 – On Section 4 I appreciate the care and research when describing the different applications and examples on what people did. Maybe it would be interesting to have one more table with all these examples listed and with links to them directly? This would allow much faster consultation for the readers? Or even another idea would be to have this on the dedicated website as a living document? This way people can add their projects as time passes? https://open-neuroscience.com is doing something along those lines with a semi-automated system, where users can fill out a form and have their projects added to Open Neuroscience. Maybe something like that would be super helpful for bringing this community together?

6 – Line 413 states a gigabit connection at 900Mbps. I am not 100% sure about this, but a gigabit connection by definition should be 1000Mbps? Is this lower rate a limitation of the Pi? Or is this a misconception from my side?

7 – Lines 567-568 talks about removing IR filters from the Pi Cameras, please add a link to a tutorial if there is one?

Major:

1 – On line 70 there is something similar: “… the most widely used low-cost computer by the biological research community”. This is a big statement, but I feel it misses data to corroborate. Could we please see added data to this (I understand the entire review is evidence for this, but the way it is now, I cannot compare it to other SBCs and low-cost computers), or have it re-phrased?

2 – line 108-110 compares the RPi to microcontrollers. Maybe it would be useful to expand this a bit more? I mean all the applications described in the paper are also a single user-written program that communicates with sensors and other electronics, so with this rationale a RPi and an Arduino could be seen as the same thing? Maybe a table comparing them in terms of costs, programming languages supported, processing power, timing capabilities, power consumption would be useful? One could also integrate the other SBCs mentioned in the paper to this table?

3 – line 115 “is affordable for anyone..” - Affordable is a really relative term. What is affordable for labs in Europe is really different than what is affordable for labs elsewhere. Even within Europe, affordable standards are quite different I suspect. Could this please be rephrased (maybe to something compare it to the costs of buying a “traditional” PC?).

4 – along the lines of the point above, on lines 404-408 there is a list of what tools people might need to get started. It would be interesting to see a table with links to where they could buy them and their costs.

5 – Lines 590-591 states that the quality and configurability of the camera modules are superior to standard USB webcams. I feel this is not necessarily true all the time? Specially if one considers that a “standard USB webcam” is a very broad term and could therefore include USB webcams that are better than the RPi ones? As companies like ELP put more and more models in the market, that can be nicely configured with Bonsai-RX, I feel this statement, even if true now, won’t be true for much longer?

6 – on line 639 there is a link for GrovePi HAT, from a company called “Dexter Industries” from what I understand the GROVE system was created by Seeed Studio and is released as open source hardware, so in a way it is fine to cite Dexter Industries, however, to give proper credit to the original developers of the excellent GROVE system, I would remove this link and add one to the SEEED studio company https://www.seeedstudio.com/category/Grove-c-1003.html?cat=890 specially because readers will them have more options of sensors and breakout boards, and also have an easier time sourcing components.

7 – on lines 695-696 there are statements about the general safety of working with the RPi due to low voltage. I understand the argument, but to be on the safe side I would re-word this in a way that makes people aware that even low voltages can be dangerous if people are working with high current applications – eg working with a peltier module, could lead readers/developers to work with 12V and up to 10A. This can be quite harmful and even fatal… I am not trying to discourage people to get their hands on tinkering, on the contrary, but maybe phrase so that they understand that there are situations where they would want extra care…

8 – a couple of times in the text it is mentioned how getting started with the Pi and programming in general is a low learning curve type of thing. I somewhat disagree with this. I mean, there are, as mentioned, wonderful tutorials for people to follow things step by step and learn as they go, but phrasing it like a super easy thing could lead to frustration when things do not work out something along the lines of “this was supposed to be super easy and I cannot get it to work” and eventually people give up. The reason I bring this up is that as developers and people already “initiated” we tend to think “if I did it, then everyone else should be able to as well” or we tend to forget the pain points and some of the initial frustration on getting started. Maybe adding a few words on how using the Pi as a tool to learn programming can be seen as a fun, project based system that will pay off immense dividends for life in and outside academia later on (even if things seem a bit complicated in the beginning) can help offset the hesitation of investing time in it?