I'm going to disagree with the "mean" part especially as it relates to Dennis/Calvin comparisons. I believe the Watterson is on record that the early Dennis was an inspiration for his strip and Calvin could be just as mean in some of the tricks he played as Dennis.

The early days of the Dennis strip were aimed squarely at adults - as the WWII generation settled down and got the Baby Boom going in earnest. The gags have an adult sensibility and that's why Dennis may seem mean because his parents sometimes think he's doing things on purpose.

These early volumes are quite good. Ketcham's art starts well and improves dramatically. He is a master at filling the panel with details - but none of them unneccessary - they all add up to contribute to the gag.

Quite a few of the jokes are very un-PC by today's standards - including one where Henry takes his 4-year old boy to a strip club!

I would highly recommend the first 3 volumes. The strip really goes strong until the early 60's when the "cute" factor kicks in. I also think that as they became aware that Dennis had a legion of younger fans, they toned down his antics to discourage copycats.

Also, there is surpringly little of the supporting cast beyond Henry, Alice & Ruff in these first three volumes. Mrs. Wilson makes a few appearances, but I really think there's ony one cartoon with Mr. Wilson in the first 3 years. And Dennis' playmates (like Margaret, Joey, & Gina) have not yet been introduced.