I see nothing wrong with them, they are what they are, a sub $400 dollar toy arcade machine.
Anyone that expected more than that for $399, with out scrounging to build their own, and really looking hard for the free or next to free stuff, is stupid.
Now, if i knew before hand, about the upgrade kit, and what it entailed etc, i would probably just buy it
and shop around for a used large 4:3 LCD panel as those are a dime a dozen now, and then fab up a fairly simple cabinet
by hitting up craig's list and scrounging it for people selling left over plywood sheets
But that is kind of after the fact knowledge.
You probably did not even know about that kit, or it maybe did not even exist at the time.
Still, it is cheaper than buying a 2nd or 3rd cabinet for more games (and less floor space)
So it is still not exactly a bad deal, considering you get a complete control panel, and the rasberry Pi etc, all set up and ready to go.
I do not know the exact dimensions of the cabinet, but since the Pi does a standard output, you could actually eventually replace the bezel panel
and put in a larger LCD, maybe a 22" might fit.
And if some day a real cabinet happened to fall into your lap, you could easily transfer all the goodies into it.
When i got my cabinets, many moons ago, MAME was not exactly a big thing, and there was no retro Pi, or retrocade, or launchbox etc
so old cabinets were not exactly a profitable thing, so i got them free or for next to nothing, sometimes with arcade parts still in them, throw in a couple cast off control panels for 5 bucks, that kind of thing.
Now days, that stuff is worth money, you might pay more for a busted ass arcade cabinet that needs hours of repairs and parts hunting, or converting, than you did for your totally working game plus the upgrades.
And for a casual player, a $399 pinball cab is something they will never touch in DIY unless someone gives them most of the parts free
And i think it is running some rendition of pinballFX or some custom derivative of it