Never use this as a daily driver for banking, email, or logging into sensitive accounts. Use it for offline gaming, legacy hardware control (CNC, 3D printers), or as a media player.
One of the biggest complaints about Windows 10 is the aggressive forced updating. Version 1507 is effectively End-of-Life (EOL). While this sounds like a negative (see below), for a dedicated offline rig or a specialized low-spec machine, it means the OS stays exactly how you set it up. It won't suddenly download a 4GB update overnight and slow your system to a crawl.
Windows 10 1507 was a landmark OS. It reintroduced the Start Menu (after Windows 8’s disaster), introduced Cortana, and shipped with Microsoft Edge (the original EdgeHTML version). However, it was also bloated by modern standards, running nearly 100 background processes on a clean install.
In its stock form, it is already significantly lighter than current Windows versions. It lacks the bloat of the subsequent "Feature Updates." It doesn't have the forced telemetry of later builds, the intrusive "News and Interests" widget, or the resource-heavy implementation of Microsoft Edge (it shipped with the legacy EdgeHTML engine).