It's official, the new Mac Mini has been announced by Apple and the long delayed post-Apple Silicon transition redesign puts the mini in the Mini. Aside from minor revisions, the previous Mac Mini was still shipping in a case first released in 2010 in the Jobs era.
Apple had previously transitioned the Mac Mini to Apple Silicon with the M1 chip in November 2020 but retained the previous design, size and ports. A revision last year gave us a hint that Apple would put a little more power inside the case, as long as you paid for it. Customers could option the Mini with an M2 Pro chip, blurring the lines between the consumer and professional categories. Apple hasn't released an iMac with a chip other than the base model, while the Mac Mini has functioned as a bridge between the base offering and the extra power of the Max and Ultra chips found in the Mac Studio and Mac Pro.
As with the previous CPU transition from PowerPC to Intel, Apple retained the previous design making it harder to tell the previous machines from the new models. The transition to Apple Silicon saw a certain amount of miniaturization and the M1 Mac Mini circuit board practically swam in the cavernous case. Owing to Apple's engineers already knowing how to concentrate powerful processors into iPhones and MacBooks, it was clear the insides had been held back in the Intel era. The new Mini proves this.

Of course for the company famous for ditching fans inside their computers, this redesign has taken a cue from the Studio when it comes to air flow and managing heat. Another cue Apple has taken from the Studio is to give the Mini front facing ports for the first time giving buyers a total of 5 USB-C ports, one less than the Studio while the USB-A ports have been removed completely (the Studio has so far kept its USB-A ports). If anything the Mini is almost a Mini Studio. In a package closer to the Apple TV.

The M4 Mac Mini can be optioned with a decent amount of memory and storage. The M4 base ships with a generous 16GB of memory but only 256GB of storage—it can be specced with 24 or 32GB and storage increased to 512GB, 1 or 2TB. The M4 Pro starts at 24GB, which can be increased to 48 or 64GB on the memory, while the storage starts at 512GB and can be bumped to 1, 2, 4 or even 8TB.
The original PowerPC G4 Mini was a bargain at $499 US and despite decades of inflation, the new M4 base model is now only $599. Unfortunately the price rising quickly as you increase the processor, memory and storage options.