If you want me to be honest, people are messy wherever you go! One of my roommates in JL left rice out until it went blue, lmaooo. But yeah, living with only 3 other people means it doesn't get insanely awful (I've seen some nightmares). JL also arranges a ton of events during freshers week which is nice for socialising -- I made friends with seven people on the first night, ended up living with them in 2nd year, and now in my fourth year I'm still great friends with them.
(One of them was from Ireland too!)
As for Salford itself -- I've enjoyed my time here. There's always some kind of renovation going on, and I can honestly say it's improved so much since my first year. The new buildings are great, the Salford Quays part is immense, and they've recently redone the SU too. I've met loads of great people, had an awesome exchange year, and I'm really glad I ended up coming here. The location is also A+, the train is <10mins into central manchester.
I'm trying to think of negative points... I guess the construction work can get a bit irritating (although it'll mostly be done by September, so I guess you don't have to worry about that). The SU is pretty expensive too.
I guess the main thing to consider is the positives/negatives for your course. (I can't help you much there unless you're applying for physics.) Salford tends to have good industry links (particularly with media related stuff, and things based in/around hospitals). If you have any specific questions free free to ask; I can't think of what else to say haha.