The only uses for it are some minor production stuff like word processing, excel type stuff and the like. Nostalgia. Retro gaming.
For getting on the internet, it isn't really usable, here are some requirements for internet:
Web Browser needs to be at minimum Internet Explorer 9, I think.
CPU requirements are interesting, I tried using the internet with an old AMD Athlon XP for an experiment and it was basically a failure, I found out later. I found out you need to have a minimum instruction sets to effectively use the internet, which the one that was missing was SSE2 instruction set in the Palomino core Athlon XP CPU.
Security is a huge issue, I would only ever use this as a stand alone computer, not that you could use the internet very well. Also don't even think about trying to connect to a modern NAS, I'm not even sure it can be done, I've tried it with my simple set up and couldn't figure out a way to do it effectively.
There is have been some people that did some tweeks to Windows 98 if I recall correctly, but I think that was like 10 years ago.
The primary reason that it's quick and smooth is that it's a pretty light weight operating system for what it was and it just worked.