Depends on how you want to chop it up, it's not a 'scam' because its not a paid product.

Not-as-advertised? Depends on how you're using it.

It strips out a bunch of security features like Defender. If you're not prone to opening random .exe files, then you'll probably be fine.

Some users didn't get the performance boost they were expecting, while others did (I certainly noticed a difference).

Driver support? Some people had issues, though I suspect they didn't RTFM. The AtlasOS instructions explicitly instruct the user to do all updates, including optional and drivers, prior to AtlasOS overwrites.