Yes they are addictive, you end up with an ongoing cycle of hogs. We have GP6 (neutered boar) and 2 sows (GP7/GP8) who don't get along with our boy so we have 2 accomodations side-by-side.
Downside- the hay gets EVERYWHERE 
Ours have their Winter Residence in the small bedroom (no door on it , radiator off , they can whitter away to DD while she does homework and wake me at 6am for breakfast).
They hay was all over their floor , even though we put covers down , and got walked across the hall to bedrooms.
Now they're in the Pighouse , I don;t have to get the vacuum out daily.
They don't smell as animals but the hay does and they need cleaned frequently (we do daily/alternate day depending how mucky they're being)
They need protected against everything - cold, heat, damp, draughts, foxes,cats,random birds like magpies or prey birds.
They love to eat so of course they pooh (lots) but its the most inoffensive pooh.
They will happily mow and fertilise the lawn, its just our lawn is cut in rectangular patches where the runs sit.
They have specific diet needs (hay , Vit C, not too much root veg -high in sugar, or fruit, not too much calcium - dark green veg is calcium rich)
They can get ill very quickly (literally "Well-To-Dead" ) so you need to 'know' them to pick it up.
You will be rewarded by the sweetest, noisiest little greedy rodents. Our boar sings
like a little chirping sparrow .
Ours are all 4yo this year , so getting middle-aged .