I read the Penguin classic version of this edited by Jesse L. Byock so I can only comment on this edition and translation. If you read a different edition your experience will be slightly different.
It is based on Viking poems written in the 13th century, although this edition is presented as prose. As a saga it covers a long period of time, yet it is a short book. My copy is 140 pages long, including a 32 page introduction and roughly the same amount of notes. It tells the tale of the Volsungs, a family of war heroes including Sigurd, a dragon slayer. However as with a lot of literature from this era, Sigurd doesn’t appear straight away. Like most Norse literature, although it is the stuff of legend, the characters are very human. They experience love, loss, jealousy, and revenge. No one character is perfect and none are wholly evil.
The thing that makes this book difficult to score is its style. I would have liked a poetic translation over a prose one as Norse poetry was complex and nuanced and I don’t know how much of that made it into this translation. The biggest difficulty is that modern readers may not enjoy it purely because of how it’s written. Literature of this era was usually written as “this happened and then that happened and he was born then ten years later he went hunting”. One chapter can be less than two pages long but cover months of time, which is jarring to a modern reader. On the other hand the saga’s place in literature cannot be denied. It has inspired Lord of the Rings, Wagner’s Ring Cycle and more. The notes scattered throughout are useful for explaining the finer details, such as Odin being in disguise and they enhance the details, but can be ignored if you prefer.
If I were to go purely on its importance it would be a 4 or possibly 5. If I went by my personal enjoyment it would be a 3 at best. I don’t think many casual readers are likely to enjoy it but if you’re looking for an introduction to Norse literature you could do worse than read this. It’s short, not too difficult to follow despite the large cast and has many hallmarks of legend. I’d like to hunt out a poetry translation if such a thing exists to see if that had an effect on how it reads.