I definitely think upgrading is worth it. Handiness is one of my favourite skills, and the "nerd brain" aspiration is the one I work on for my sims most frequently :)
My favourite upgrades are the fridge and stove ones, the laundry upgrade that enables you to put flowers in the washing machine, the one that gives you more tv-stations, and the ones that make bath and shower times shorter.
Never had an issue where an upgrade wouldn't work. Just have to be careful not to accidentally "replace" an object that's been upgraded :)