Running on an Atom-based SBC I had on the workbench, it's even more responsive.
Yes, building native apps requires at least a basic knowledge of C++. No, it won't seamlessly run the latest React SPAs as well as Chrome. The driver situation isn't as good as (say) Linux or FreeBSD.
And yet, the focus on providing a productive environment for normal computing tasks instead of endless up-selling to an app store, countless background updaters, and vendor-bundled crapware is like a breath of fresh air.
This is what we've lost in the move to impose ever more layers of services, unique per-app GUIs, and ubiquitous (even gratuitous) packaging of "webapps" in lieu of targeted, native apps.
To be clear: this isn't a unique property of Haiku. A nice clean install of FreeBSD or Debian has many of the same properties, and I have reason to believe that a Windows 10 "distro" based on something like Server Core could be similarly light and responsive.
Unfortunately, the major platform providers seem deeply uninterested in building systems that don't push you aggressively towards newer hardware, loads of subscription services, and "strategic" software bundles no one asked for.