2025-07-30 In praise of GitHub Copilot code reviews
GitHub Copilot will now do code reviews. I’m a fan, but it turned out several friends aren’t. So I wanted to talk about why I really like them.
The key thing from my perspective is that Copilot code reviews are not the same as human code reviews [1]. They are substitutable to a point, but not entirely substitutable, and that’s an important distinction.
Copilot code reviews aren’t as good as a good human reviewer, but they’re hugely cheaper, and that low cost brings a bunch of benefits.
In the literal dollar sense, Copilot Pro costs $10/mo and offers some unclear number of code reviews - but even if it were $10 a review, consider how that compares to a colleague’s hourly rate.
But it’s the implications of that low cost that are the most valuable and interesting to me:
Sometimes there is no human reviewer. A current side project of mine involves porting a C codebase to Go - I’m currently working solo, there’s nobody else who’s going to review my code - I’ll take a Copilot review as better than nothing! If I had a human reviewer, I bet they’d give me a bunch more valuable feedback. But I don’t.
Even when there’s a human reviewer, Copilot saves time and energy. Copilot can review my PR before a human has had a chance, which means it can find (potential) issues sooner, even if they’re only minor. I use formatters and linters because I want computers to handle the trivial stuff so humans can focus on the more interesting bits - I see a Copilot review as much the same. It can read a ~2000 loc diff in ~1 minute and tell me I’ve probably used the wrong exit code, and I can get that fixed before a human has had a chance to even load the diff.
Crucially I still want a good human reviewer if and where I can, but if I can’t then this is better than nothing, and even if I can then this helps their load.
Is it definitely better than nothing? I believe so. Sure sometimes it suggests things that don’t feel valuable, but so do humans - my experience so far is that these are a combination of minor, matters of taste, and infrequent enough to not be a distraction.
Copilot code reviews are no substitute for good human review. But they’re still helpful.
And this is basically where I’m at with the current state of AI tooling: people will try to sell you on “replacing humans” because that’s enticing to the folks holding the purse strings, but that’s not the reality - but don’t disregard the value as a force-multiplier.
Note
In a wonderfully serendipitous example, Copilot caught that I’d mangled the rST footnote syntax when I first pushed this post!