Oh well, if we are going to keep the necro going...
I recently picked up a 500 and 1200, and a 1084S monitor. I'll describe my experience with it thus far.
It came with a box of floppies, unfortunately most of them had deteriorated over the years so I'd get errors trying to use them. I had to give my cleaning floppy quite a workout as the old disks would dirty the heads.
The 500 only has a floppy drive so was pretty much useless without any floppies. Even the original Workbench 1.3 disk it came with was dodgy.
The 500 also had a RAM expansion for the trapdoor slot underneath. This had a battery backed up clock but of course the clock had one of those terrible PCB mount barrel style batteries which had leaked, so first task was to get rid of that. If you get any expansion with a clock be mindful of this.
The 1200 had workbench installed on the hard drive, but of course to get software onto it via floppy you need to put tape over t he notch on your disks and format them on your PC as 720KB. Then the amiga can read them, but you need software to do so. Luckily I had a working floppy with dos-2-dos on it, so I used this to copy utilities I needed such as unzip, LHA, and an ADF image writer.
Basically getting software onto it was a major pain in the arse.
Pretty much all the disks I wrote, seemed ok in the 1200 but the games/demos etc would be glitchy, presumably because of the AGA chipset.
The 500 would get errors reading these disks.
It should also be mentioned that if you format a 1.44MB disk as 720KB or use it in the amiga as an 880kb disk, they are more prone to errors than a true 720KB or 880KB disk.
Thankfully a couple of local amiga enthusiasts came and got me sorted out with a CF card and IDE adapter, with classic workbench with all the utilities installed.
You definitely should look into Classic Workbench if you get a 1200 as it makes things a lot easier however the installation can be quite involved. You also need a working Workbench 3.0 or 3.1 disk to install it - which I didn't have. My workbench floppy had errors.
Once that's up and running you can get a PCMCIA CF or SD card reader, and transfer files to the amiga 1200 that way.
So its been interesting so far. The command line is a lot different to DOS and unix/linux which are the only operating systems I've really used. The manauls I had didn't really explain the commands in any sort of detail and the workbench GUI is quite spartan- not much there if you don't know where to look.
Some of these guys buy accelerator cards and RAM expansions for their Amiga, then use a flickerfixer to run it with a modern LCD monitor, and use it as their primary PC for surfing the web and so on. I don't think I'm that keen on it, and those accelerator boards can be a couple of hundred dollars or more. A bit rich for me I fear.
I'm mostly enjoying downloading demos to run on the Amigas as they are definitely more impressive on authentic era hardware. Most of the games I like are available on PC, although it can be interesting to compare the differences between versions.
Overall its an interesting machine but I wouldn't go too far out of your way to get one.