Suffice to say that whilst it is capable, the success rate will be diminished compared to when it was a current machine.
On the face of it, this seems like it would inevitably be true, and I'm not so much arguing against the point being made as adding a bit of a caveat.
It won't be much good for web browsing, but when used with software of the day (and some since) it is just as capable as it was then. What it likely isn't going to be very good at is running a lot of software that is newer.
As an example, I use my G4 iMac for Word 2008, which is file compatible with later versions, so is very usable, and it runs very well. I also use iMovie HD for editing video, which also works very well. Photoshop Elements 2 runs on it for editing and adjusting photos, and a little ironically perhaps, web authoring in iWeb also works - which it doesn't so much now. Naturally, that might not be a selling point since it was rather awful! And while I never used it myself, the iLife 06 version of Garageband also runs pretty well, and used to be in regular and creative use in my household on a MDD G4 back then.
There's likely to be a lot of era-appropriate software in places such as macintoshgarden.org for productivity, gaming and the like, and it may be worth the OP looking around there, and macintoshrepository.org to see if anything PPC compatible matches his interests.