I'm using it to aide in writing pytorch code and God if it's awful except for the basic things. It's a bit more useful in discussing how to do things rather than actually doing them though, I'll give you that
o1 seems to have some crazy context length / awareness going on compared to current 3.5 Sonnet from playing around it just now. I'm not having to 'remind' it of initial requirements etc nearly as much.
I gave it a try and o1 is better than I was expecting. In particular the writing style is a lot lighter on "GPTisms". It's not very willing to show you its thought process though, the summaries of it seem to skip a lot more than in the preview.
o1-preview was less intelligent than 4o when I tried it, better at multi-step reasoning but worse at "intuition". Don't know about o1.