Positives:-

A welcome home

Company when alone

A reason to exercise

Can be non shedding / "hypoallergenic"

Funny & playful

Something to cwtch

A watchdog / guard dog (perhaps)

Cute factor - love (?)

Negatives:-

Need to train (successfully)

Cost :- Food / Insurance / vets bills / kennels / equipment / calming drugs / treats / haircuts

Smell

Noise

Need to exercise

Destruction of things

Pain for guests

Need to look after ( kennels)

Need to attend

Getting woken up / disturbed

Clearing up shite

Bites

Fur/hair - shedding

Annoyance factor - hate (?)

Why on earth didn't we do this before getting a dog?

Would we do it again?