Like most of the people who will be interested to buy this DVD, I watched Moomin when I was little, and then missed it for a long time between it disappearing from normal TV broadcasting until recently becoming available on DVD. And as such, I'm not disappointed - all those episodes collected in one place in a digital format - great!
As many other reviewers have mentioned, the sound and picture quality are not up to 'today's standards', and though the series was made a good few decades ago now, I can't help but feel that if they'd really wanted to they'd have managed to clean it up a bit for the DVD. If you want an idea of what the quality is like, I don't think it's any worse than it would have been off your TV 20 years ago. As far as I'm concerned, it's fine.
I was a bit concerned when starting the first episode, that the audio had a slight but distracting echo. However, this does not appear in the rest of the episodes, as far as I can tell. One other problem is that on the second disk, the first and second episodes are the wrong way round in playing order, creating discontinuity if you're trying to watch all in one go. There are no other language options than English, and no subtitles at all. The DVD menu gives you just 'episode 1', 'episode 2' etc, so you have to refer to the back of the DVD box to know what you're selecting. Those are all the problems as far as I've found.
If you're unfamiliar with the series but are considering buying the DVD for children, then it's a fantastic choice. I'll never cease to be horrified by the incredible crap TV that's made for children these days, and if you want something stimulating, thoughtful and entertaining to give children via a TV then you're much better off referring back to the 80's stuff like Pingu, Thomas the Tank Engine, and Moomin, to name a few. The age range for all of these examples is great too, from toddlers to 8 year olds being the ideal, in my opinion. Myself, I still enjoy Moomin and Pingu at 22 years old, which must say something good about them. The stories are structured, the characters are engaging, developed and entertaining, and there is plenty of excitement without being too scary (the classification on the back of the DVD is 'mild threat', to be specific), and there are many lessons and 'morals' in the stories.
In summary, whether you're buying for nostalgia or for a new young audience, this is a perfect choice. As long as you don't mind the same quality as analogue TV, a couple of minor mistakes on the DVD ordering, and a lack of language and subtitle options, then you won't be disappointed (escpecially for the price Amazon are selling it for).
N.B. Incase you haven't noticed, there are also three more DVD volumes of Moomin available to buy on Amazon, with many more episodes. I've bought these too but as I've not yet watched them I will return later to review them too.