It's an interesting job and it's very different from any other work I have done before. Unfortunately, it's only on occasional basis for me but I guess that depends on the language you work with. Polish interpreters might do this on part or even full time basis, since there are far more Polish people in Ireland. Interpreting in courts might be quite challenging if you're not familiar with the law terms and also, the courtrooms have very poor acoustics. Working in Garda stations is something I enjoy the most.
You are not their employee, you work for them as a freelancer, so you are responsible for your own taxes.
meeting new people, discovering new places, great opportunity to improve your second language
very short hours, travelling takes up too much time and you don't get paid for that time