Well it's ranking is crap and you'll have to put up with the rivalry of living in the worst uni in a small city.
Saying southampton uni people take the piss a little bit is a very, very large understatement. Last time i checked about 10% of the southampton uni population were on the 'Southampton Solent isn't a real university' facebook society.
But then again what other students think of your uni should mean feck all to you, what employers think of your uni is another thing entirely and unless you're doing something maritime related the Solent university's reputation is rubbish. Until recently it wasn't even a university. On the side of their building they have a large poster advertising their lecture theatre! (wow, like, hardly any unis have those!)
If you get a conditional offer from somewhere better, take it.