Lived in Limerick for 6 years, would move back there in a flash!
The reason for lower rents and some houses lying vacant in the college areas, is due 1)oversupply, however when I first moved there (7 years ago) you couldn't get a room for love nor money, and 2)those lying vacant are mostly slums, in that they are damp, miserable houses that used to house mainly students during that time when there was a huge shortage, now that there is a decent amount of better accommodation, i.e. new houses and apartments, these aren't being rented!
As for the horses and sulkies, yes you will see these on a regular basis, and yes it would annoy some, however it's not bad per se.
Scangers in the city - there's a hell of a lot more scangers elsewhere than in Limerick, but this is the case in ALL cities.
In my 6 years living in the city (and 18 other years in the county of Limerick), I never once saw a 'riot', or encountered any major fights. I have, however, come across this is other places, and wouldn't brand those places as 'dangerous, rough' places just because a bunch of yahoos caused problems.
IMO cities in general are going to be rough on occasion, simply because where people congregate, trouble can occur (esp when alcohol is involved)... Limerick does not have a monopoly on this!
As I said we'd move back tomorrow if circumstances allowed, we hated having to sell our house there, but renting wasn't an option for us.
There's the colleges (UL, LIT, MaryI, NCAD), the sport, the schools (of which there are some excellent ones), the city is dinky and has plenty in it, the Shannon, lower prices on nearly EVERYTHING.... I could go on and on!
The media have a lot to do with the branding of Limerick as a rough place, there's more going on in Dublin and it's environs every day than what happens in Limerick each week, but the media are tired of Dublin, a lot doesn't get reported nationally, and therefore I can understand why some people have distorted views of other places because of this...