I have lived in Swansea for the last 5 years and I think it’s got a lot better in that time. I find some of the above comments a bit offensive tbh.
For nice places to live look West. Start in Uplands/Sketty and keep going towards Mumbles/Newton/Bishopston. Mumbles and Gower are nice but more expensive. Alternatively there are lots of new flats in the SA1 Waterfront and marina areas if that suits you. Most of the student areas are nasty but fortunately the students don’t leave them much.
For bike routes there is a cycle path that runs along the side of the Fabian way most of the way to Llandarcy, it’s a shitty cycle path but does the job. I regularly used to do Swansea to Port Talbot but we’ve now moved to a posh new office in the SA1 waterfront. Cycle commute along the bay is incredible on a sunny day. There is also a cycle path going through Clyne woods which a lot of people use.
Happy to show you some local trails beyond the obvious ones at Afan when you get here. Lots of good technical riding up Kilvey Hill for example.
cheers
Jonny