"Pretty much everything Windows 95 did, ten years earlier."
Seriously, that's how I try to explain it these days. Multimedia? Check. Multitasking? Check. Right-click menuing... Well, nobody knew that'd come into vogue, but for all we know, Apple's one-button solution could've been the fad without.
The problem with 'defining' the Amiga is that, when you look back, many of these things had been done in some shape or form, sometimes even placed on the commercial market. But it took the Amiga team and Commodore's investment to put it all in one plastic box (was that the reason for all those grounding problems?) and point it straight at the world's living rooms.
In the end, you got this thing that looked and acted (to stretch a friend's analogy) like a cross between an Apple II and the triumphant desktop of a decade later. At the time, it was the first "home" (perhaps simply based on Commodore's market position) "Personal Computer" that wrapped it all up in one package -- sort of like people keep going on about the ST for including MIDI, even if that was a much lesser technical triumph, or Mac for putting the mouse in the box at all -- it stood up and said "Hey, what are you waiting for? Computers can do this stuff," where 'this stuff' was an amalgam of all the best practices being/already devised in labs and corporate installations and universities.
What did people buy it and do with it? Well, "computery stuff," which is why it's so darn hard to pin it down; you could tighten bolts with a wrench, but the introduction of the ratchet made things go so much smoother... Can anyone here pinpoint when that was introduced or what it changed? :-)
...Of course, way back when, all the manufacturers who'd touted the ergonomy of their wrenches, or the danger of the springs unwinding, or really believed in their heart of hearts that everything should be put together with velcro, started making ratchets, too. It was too obvious an invention not to. How many people remember this "Robert Owen, Jr." guy I just looked up on Google?
Maybe the real impact of the Amiga was getting everyone to look up (slowly but surely) and say "Holy cr*p, we better pay attention to hardware!" People had that idea, too, but few were completely prepared for a machine that got over so many little bottlenecks at once, and those who were (and one might've hoped would be the biggest hornblowers) kind of shrugged it off as a quirky miracle of Moore's curve... then went on to weave the magic into their own designs, to be released once the market was primed for it.
(As Info-64 wrote about the launch, there was awe enough throughout all the demonstrations... but a real hush fell when someone popped in a copy of Translator, and Lotus 1-2-3 took its slow, monochrome crawl up the screen. There's a theory floating around that 'systems that emulate are doomed to failure,' but I think we're now seeing it's more complex than that -- on the 1000, with its limited RAM and CPU, you were running at 'native' speeds, and probably weren't going to open two copies at once; the 'magic' was lost on you if that's what you were forced to work with all day. OS/2 had some similarly good ideas a few years later, but resource limitations meant it was still more of a one-or-the-other thing. By the time MS, with their penchant for market-timing came around, it was not only possible but easy for a 486 to demo a couple DOS programs running at once, and 'Runs your existing software.. better!' makes a much better proposition than 'Runs your existing software.. with the same limitations you're saddled with now!')
Of course, there're millions of other reasons why one died out as the other took off... but that goes to demonstrate its strengths and failings in the hours before everyone rushed to take over its market.
