The 1200XL was my first computer. My family purchased it at a department store at a fire sale price (IIRC Montgomery Ward's, $199) after Atari stopped manufacturing and began dumping its inventory to make way for the 600XL/800XL. I had been researching a computer to get for ages, but my family was very careful about how we spent money, and it was a big purchase. We had seriously considered getting a TI-99/4A when TI exited the business, but we were concerned that it was just going to be a dead end. But the chance for a cheaper entry into an established ecosystem was great (that and me begging my mother to finally, finally get a computer!).

Re compatibility, I never came across software that didn't run on it. I'd read in magazines that there were issues, but never once experienced it. One interesting software change, though (but true of other XL computers, too) was that the color "artifacting" worked differently on it than it did the 400/800. For example, Ultima III used color artifacting, and so playing it on my system produced some incorrect colors...most notably the sea was red.

I did come across one hardware issue...a cheap third-party parallel interface adapter that didn't work, and that we thought at the time was defective, but I now think it's likely to have been affected by the incorrect power wiring in the 1200XL's SIO adapter. It was cheap enough that we didn't lose too much money on it, and I ended up getting the far superior ICD P:R: Connection instead.

The Atari community was a super great community to be in. And in so many ways, Atari was doing things that wouldn't be seen again for years, if not decades. Atari's SIO port is famously a predecessor/inspiration of USB. The APX Exchange was basically a third-party app store decades before Apple popularized the concept. The machine was hackable and moddable (I bought a 256KB upgrade kit for mine). When I migrated to PC for college use, it hurt to have to fall back to CGA...even EGA was just ugly, compared to what my 1200XL was capable of (although the 80 column displays were nice compared to Atari's 40-column).

My first owned computer was a 1200XL as well. Found a game that read raw keystrokes and that was different from the 400/800 to the 1200XL.

I patched my copy of the game and sent the patch to the publisher (Microprose, IIRC) but never heard from them.