This was my first time building an arcade unit. I purchased the 5:4 version of the cabinet & I built a pc inside rather than using a raspberry Pi so I will focus on this; hopefully it will help some prospective builders.
I did a lot of research looking at various designs before I finally settled on this. There were much cheaper designs elsewhere but this was definitely worth the extra money as it's nice and thick, the components all fit together well,all the screw holes are clean and accurately placed, the instructions are good and it comes with all the screws etc you need.
The cabinet does have a bit of a mottled texture so if you want to paint it and get a smooth finish you will have to spend a lot of time sanding the surface down before & during layering primer & paint.
All my additional mounts I did by drilling out the holes & using threaded screw inserts like the ones that come with the kit. I did find that making modifications through sawing/drilling would sometimes cause the material to splinter and split a bit but it never split right through.
This next bit is mostly about building a PC inside:
The interior is quite compact towards the front where the control panel sits so when building a pc into it I found that only a micro atx board and a low profile fan (stock intel is fine) would really fit. I installed mine with the cpu towards the front of the cabinet and the rear connectors (usb,VGA etc) running up the inside depth of the cabinet so that I could fit a 2 slot graphics card in behind the monitor, which is the only place with a lot of verticality.
If you're using onboard graphics then you might prefer doing it a different way to make it easier to access the connectors but try and keep the motherboard as far back in the cabinet as possible because of the button/joystick clearance needed at the front.
For cooling I didn't feel that the 80mm fan/speaker slots on the back would be sufficient or provide good airflow for a pc so I cut the lower 80mm to fit a 120mm intake fan & covered it with a removable filter grill. For air outtake the top of the marquee has preexisting grills that I mounted 2x 80mm fans to the underside of, this still left enough space for a couple of small speakers (cases removed) and the LED strips to light up the marquee.
The back of the monitor bracket was ideal for mounting hard drives and I fitted a standard sized power supply on the bottom of the cabinet opposite to the motherboard; I didn't have a modular PSU spare but would recommend one to keep the case tidy.
I also added a wifi card & bluetooth dongle and neither have problems penetrating the casing. I also bought a splitter cable that allowed me to plug into both the monitor & the PSU so you only have 1 wire going out of the cabinet instead of 2. Finally I found button blanks great for cutting and mounting rear connectors onto such as extra USB or feeding through the power cable. There's already 4 holes cut on the bottom to accommodate these and it means less dust getting in.
I'm very happy with the final product but if you want to build a pc inside then I think this is the smallest size cabinet you could get away with.