I have a 3 year old border girl. She’s the sweetest natured little thing - cheery, eager to please, completely loyal and bonded to our family (likes to be right next to us at all times), playful and loves children and dogs. She has never once snapped or shown any indication of bad temper - she is as soft as butter and full of fun.
In terms of exercise, she does love a good run and gets 1-2 hours a day and will happily go on really long hikes with us - but on the odd days we can’t manage nothing bad happens. She just potters around the house with us and isn’t destructive and doesn’t whine.
If I were to identify downsides, I’d say we’ve never managed to stop her from jumping up. As soon as someone makes eye contact she assumes they want to be her best friend and gets very excited (and is often rewarded by people making a huge fuss of her!).
She occasionally goes deaf if there’s a squirrel around but her recall is 95% reliable. Recall took a while to knock in - until she was about 12-18 months she was so sociable with other dogs she’d just spring off to play with them But has calmed down massively on that front now.
She’s also very very bonded to me. Whilst she clearly loves and makes a fuss of her family, there is no doubting that I am her person and she’d always choose to sit with me, wait for me and behave best for me (her selective deafness happens more with DH). This works fine in our family as she’s not preferring one of the kids over the other - they at least get equal treatment!
Picture of her happy little self on DC’s bed.