Wow, I'm really surprised. I tried deepseek (their best model, through the official API). Its extremely cheap, but its clearly not as good at programming as Opus 4.7. It seems nowhere near as good at making high level design choices. Deepseek also seems to get stuck in whack-a-mole fixing loops much more than opus. I stopped it at one point, and asked opus to solve the problem it was trying to solve and it saw the solution immediately.

I was running deepseek through claude's code agent harness. Maybe it works better through a different tool?

interestingly I had the same experience, and weirdly it's in part because it is clearly less intelligent. It's more of a mechanistic tool just doing what I ask (but still very smart and very competent about it) and less trying to win a nobel prize with each answer. Turns out I actually like that.