has anyone used it? what do you think of it? Is it worth it, especially compared to the free plan?

I think the plus plan is expensive (I don't use it for programming), but my main concern is that go doesn't have any reasoning models.

thoughts?

I consider reasoning to be a huge quality differentiator particularly for complex questions/medium+ length discussions.

Low-Thinking/non-Thinking absolutely has a place, but not in a tool like ChatGPT due to its very nature/designed purpose. Low-Thinking is useful in simple tasks/utilities where it is a straight 1:1 between the source and destination, like automated workflows.

ChatGPT Instant simply isn't worth using for the task they're assigning it. Medium Thinking is passable but High or better has a marked quality improvement/reduction in hallucinations.

Thinking isn't anything to do with logic/arithmetic/programming; it simply allows the LLM to spend longer deliberating/second-guessing itself, rather than looking for the shorter path to a supposed "answer." A LOT of mistakes get washed out in that second-guessing step (although of course mistakes can still occur YMMV). This lack of mistakes does make it better at logic/arithmetic/programming, but it also makes it better at everything else too.

I believe Google's Gemini gives you a handful of free Thinking credits a day, I'd give that a shot and I believe you'll see what I mean.