I have a 2yo JRT x Dachshund - but the JRT is clearly the dominant side of the mix. He's my first terrier.
The first thing to know about him is that he needs at least two hours of brisk walkies per day, ideally in a dog heavy area. Every day. Anything less than this and you will live to regret it - he'll be biting your ankles and generally making a nuisance of himself. If he gets overtired he's like a toddler throwing a tantrum ("I blame the parents" said a 'helpful' woman at the ice cream stand this weekend
). I work hard to keep him somewhere inbetween undertired and overtired!
He's pretty feisty and has a bit of a tendency towards reactivity - I've learned to manage it now with professional help, and he's generally a great dog (inc. with children - I've tested him with well behaved 5-8 year olds), but let's just say that I've learned a great deal about dog behaviour from having him around and researching out of necessity. How much is because of his background of zero training and multiple rehomings? Very hard to tell; I suspect it's a mixture of nature and nurture because he has improved enormously.
He's utterly obsessed with balls, and will never, ever give up on a game of fetch. He might have a breather, but once he's got his breath back he'll be straight back on it. Loves to chase rats, squirrels, magpies etc. but has never caught one. Not much of a digger or a barker - which is highly unusual given the breeds!
Definitely a one-person sort of dog. He only bonds to those who are his primary carers, but he bonds to those people very, very strongly. Family members who are often around but don't take him out for walkies? Ignored, unless they have food. Strangers who try to attract his attention? They might get 3-5 seconds of attention and then they'll be ignored. Me? He's clearly devoted, doesn't want to go too far when off lead and checks in every 10 seconds or so (it's quite sweet really). Some of this may come from the dachshund side of the family, some may be a nurture thing (after 10 months, I've been his life longer than any of his previous humans).
He's a great dog - now - but full of idiosyncracies and in great need of careful management to maintain his status as "acceptable member of society". If you do get one, for goodness sakes go to well run puppy classes (not the type that are a free for all with puppies jumping on each other) and socialise him in a variety of environments, urban and rural, to give yourself the best chance of a well rounded dog. Or - even better - get a rescue - there are a huge number of JRTs in rescue 