1. It writes SO MUCH code, in minutes, that theres no way I as a human can review it.
2. I am not very motivated to read/review this code anyway: it was cheaply written, by some _thing_ that is not going to improve from my feedback.
3. If you DO review it conscientiously , it becomes a never ending thing: you keep finding issue upon issue.
4. If you report the issues for fixes, the fixes normally fix that immediate issue, and typically add another parallel path/another option/another 100-odd lines of code, instead of a structural fix.
5. If the code base is large, and if you let AI write a meaningful amount of code in it, its no longer _your_ code. You lose the depth+width of understanding needed to reason thru things mentally, cause you no longer KNOW enough about the code.
6. If you do review seriously, and either fix things yourself, or have the ai/harness fix the issues for you, the rounds of fixes take so long, if you look back you realize it would have been better to just do it yourself in the first place.
My personal opinion there are really only two choices:
A. If you want to build FAST, using an agent, just let the agent write tests, validations, extensively, have it keep running them (it likes to call them gates), and just let it loose. Give up on the idea that its your code, and that you understand it. The bottom line becomes: does it work, and WHEN it breaks in weird ways, just use the agent to find and fix the issue (probably breaking something else in the process).
B. limit AI use for non trivial, prod-quality projects to limited research, very tiny targeted changes, write most of the code yourself still, and review every line. You won't get much speedup, maybe 20-30%, but it will still be YOUR code, and you will still be able to reason about it.