I'm not sure I can do Sheffield justice in a 5 minute coffee break post. But I'll try.
Here are some things I like about Sheffield
The look of the place - A bizarre mix of ruthless 50s and 60s brutalist modernity and massively quaint old things you don't see anywhere else. Yes abandoned factories can be depressing, and are the scars of a truly desperate time in this city's history (25% of ALL JOBS in Sheffield were lost in 1984), and they deserve better than to just be curios to be gawped at on Sunday walks. The same goes for the massively ambitious social housing projects from the 1950's and 60s. But there are some fantastic looking buildings here. I wouldn't even say I was interested in the built environment before I came to Sheffield, but after a few years here I'm planning a bus trip to Preston to catch a glimpse of the bus station before it gets knocked down. The hills can be insane, You can walk 2 minutes from the 21-story Royal Hallamshire Hospital and lose sight of it behind a hill. You can walk into the front of a building at street level, walk up three flights of stairs then out the back and still be on street level. It's a pain at first but you soon get fit, and it's worth it for the vistas. Just stand at the top of Blake street, or on Skye Edge if you don't believe me.
A refreshing lack of wankers - I notice this more when I'm out of town. There are of course plenty of wankers in Sheffield, but noticeably less than in a lot of other places. Mixed up in this I think is the fact that for the vast majority of Sheffielders, it doesn't do to be flashy or snobby*. Smartly dressed, passionate, member of a youth cult, fine. But there's very little of looking down on those that can't/don't choose to do the same things as you. No-one seems unapproachable. Again, this is probably a product of recent and ongoing hardships in the city. There are very few people with stupid money here (compared to say London or Bristol), and I'm sure as a result of that, those that have silly money don't make it known - but it is noticable, especially when you leave.
Cheap living - You can buy a terraced house in a perfectly nice part of town with good trams and buses to town for £150,000. Or in a more lively part nearer the centre for less than that. You can't rent a perfectly good room for £60 a week. Even a 4 bedroom house in a very nice part of town shouldn't set you back more than £250,000. Beer is cheaper and better than anywhere else I've ever been. Food is cheap at Castle Market. Life here is relatively cheap and people are happier because of it. I'm convinced.
Beer - Cheaper and better than anywhere I've ever lived. And the pubs are properly friendly and appreciate that beer is the ultimate discretionary purchase. Kelham Island is a joy, but even nightclubs will have at least one decent well-kept ale on.
Independent shops etc - Yeah, I know every town reckons it has brilliant independent shops and that. But Sheffield does for sure.
Countryside - When I moved here I was completely ignorant of the closeness or aceness of the countryside surrounding Sheffield. And I wasn't particularly interested in outdoors stuff anyway. Now I'm out in the Peak District most weekends doing something (mainly fell-running). You can get to breathtaking countryside within 15 mins of the city centre for a couple of quid on the bus. It's astonishing to be so close to a proper city and proper countryside.
Apologies for the brain-fart. I have to get back to work now.
* Apart from a few of course, but they mostly stick to Nonna's and Menzel's on Ecclesall Road on a Saturday night, so they're easy to avoid.