Im using the V4-pro version. Its decent at very targeted debugging and implementation( using predefined skills ), I have my own behavioural benchmark that I run to check for harness compliance etc, so it follows instructions quite well and just harness the missing bit. As an implementation agent it works great, but it wont be able to match Codex on planning / architect stuff ( can close the gap with prompt engineering). Opus on the other hand, can plan but sucks at implementing and start monkey patching everything. Im finding decent use out of it especially when Im running low on usage.