I've lived here over 20 years and can't see me leaving.
It's a very attractive and compact city with the docks, Suspension Bridge and lots of green spaces. Great for mountain-biking with all weather trails in both Ashton Court and Leigh Woods which are just over the Suspension Bridge and very handy for trips to South Wales trail centres, Forest of Dean, Mendips and Quantocks. Also great for road riding.
As noted above there's lots to do in Bristol from a cultural point of view - festivals, gigs, exhibitions - and has some quite unique events for example the recent Gromit trail, the grafitti in Nelson Street and the Banksy exhibition a few years ago. Loads of pubs and restaurants to suit all tastes and budgets.
Its quite a green city (won European Green Capital bid, and was previously Cycling City), so quite a big alternative scene, and has more bike shops than any other city I have been to. Has a weekly Farmers Market and host things like a Vegan Food Festival. Lots of charities, community groups if you feel like getting involved in the city. Also home to the mouthwatering Pieminister pies.
Downsides are traffic, resident parking zones, property prices / rents, bike theives, local politics, local football teams, too many supermarkets.
Places to look for rented accomodation would be Redland, Cotham, Kingsdown, St Andrews, Bishopston, Horfield, Clifton, Southville, Totterdown. I personally would look around the Gloucester Road area as its a really vibrant road with lots of independent shops - Bishopston, St Andrews, Horfield - and has easy access to the city centre.