I've been using a Raspberry Pi 3 for a couple of years now as a workstation, but only as multiple terminals, plus a bit of Googling. When the Pi 4 came out, at first I couldn't get hold of one, but after a while they became easily available.
You can get them in 1gb, 2gb and 4gb. But you can't upgrade. The cost is £35, £45 and £55, so I got the 4gb version. I also got the recommended power supply (I can try it out later with my own power supplies). My own? I'll just explain that.
I use standard PC power supplies (and in some cases, they are powering an ordinary computer). I take the 12 volt line, and feed that into the ethernet cable, using a POE adaptor. Ethernet cables are 8 wires, but only four of them are used. So this uses the other four to carry power. Then I feed that 12 volts (which will have dropped a bit by the time it arrives where it's needed) into a little card that drops that 12v to what the Pi wants, which is about 5 volts (or maybe 5.5). This means that I don't need lots of Pi power supplies; that little card is very cheap. And it means I don't have a big overhead in the power conversion.
I set up a 64gb SD card using the latest Raspbian, Buster (I only recently found out that the various versions are named after Toy Story characters). But then I hit the first problem - I only have HDMI cables, and the Pi 4 uses mini HDMI. So on Ebay, I bought a little converter from HDMI to mini HDMI.
I plugged in a USB keyboard and USB mouse, and powered up. To my great happiness, the Pi 4 was immediately driving my Acer et430k monitor giving me 43 inches of 3840 by 2160 loveliness. I was half-expecting to do a lot of messing about for that, but it "just worked".
The USB keyboard is rubbish - what do you expect for £4? But I was able to replace that with one of my beautiful big IBM keyboards (you can still get them, they're about £100, but if you do a lot of typing, and like a positive clicky keyboard, it is perfection). That has a PS/2 interface, but I have a converter for that, and that worked first time too!
But the sound didn't work. The HDMI interface should feed sound into the monitor, and it wasn't working. I haven't given up on that yet; I feel that the problem is at the monitor end. But I do want sound! So I used the audio output on the Pi 4, and fed that into a pair of powered speakers. And that worked first time too!
So then I added Firefox, and xfe (the file manager that I like), and Nedit (my favourite editor). A slight problem there; most of my computers are Fedora, and I know how to add software to those using yum. But the Pi 4 is using Raspbian, a derivative of Debian, and that uses apt-get. I think all the packages I want are probably available, but the names are slightly different. Google gets me there.
And printing. I have three printers, my Old Faithful HP Laserjet 6p, which I've had for 25 years. That was very easy to set up because I use Jetdirect, an ethernet-to-parallel converter. The Dell was easy too, because it is natively a network printer, and the Samsung took a bit of messing about to get that working with the Pi 4.
Networking can be done using the built-in Wifi, or the Gigabit ethernet port. At first, I used the Wifi, but it didn't play youtube smoothly. So I used a speed tester on it. I found that my various Wifi access points were giving me 5mbps, 7, 10 and 20, with the 20 running off the TP link. But with a wired connection I got 60 mbps, which is about what I'd expect, because my link to the internet is 100 mbps. Roll on Gigabit broadband!
So what's the point of all this?
The Raspberry Pi 4 takes about 2 amps at 5 volts, which is 10 watts. When I put my hand above it, I can feel that it's slightly warm. But that is replacing a full size computer that was pulling about 150 watts. And it isn't just the cost of the electricity. It's the heat. All that 150 watts comes out as heat, which isn't a problem in winter, but we had a really really hot summer this year, and even opening the window didn't help, because it was hotter outside than inside. But next year, when the hot weather arrives, I can power off all my computers in the office except the Pi.