I've been playing for just over 100hrs solo (vanilla) and loving it.

The bronze age was a bit of a grind but after that I found things sped up in terms of iron which allows you to get kitted out in a fairly robust set of armour and weapons and opens up more building options.

I've no desire to play MP as I want it to be my world and done at my own pace. However others clearly like the MP aspect so I think it comes down to what sort of gamer you are; there is no right/wrong answer.

Lots of similar questions on the board; this one from a few days ago my be of help if you search for it:
"Should i even bother solo? Is it supposed to be played with multiple people"
...sorry, can't see how to link to it.