I'm one of the casual staff in food and beverage at a local hotel when I'm at home.
I'd say the biggest benefit is that you work when there's work available, and you can work when it suits you. Obviously I wouldn't turn down loads of shifts because there's a chance they'd just say forget it, but if you can't work a certain day or weekend or whatever, it doesn't matter because you're not contractually obliged to work then. At my workplace, it depends on the time of year as to how much work is available - there's usually a lot at the weekend over the summer because that's when most people choose to get married, and I got quite a lot of shifts over Christmas as well; however when I came home from uni for Easter this time there was no work available for me because busy wedding season hasn't started yet (both good and bad - I've been less stressed about revision, but I could really do with that extra money right now!). Hopefully when I come back in the summer things will pick up again.
I don't know if working in a bakery would be similar, but I find the job can be quite stressful, especially when it's busy, because there's always something that needs doing. The bar's quite hard to run sometimes if it's a cash bar and there's a long queue of people building up and you're someone who gets stressed out really easily. Also the pay's not great where I work, but it's still more than I'd get if I didn't have the job. I applied for jobs at loads of places when I finished my first year of uni last year and they were the only place that got back to me, so I was lucky that they offered me a job!
Even if you don't like the work, it's worth doing just for the money until you can find something else. I'd certainly have really struggled with money this year if I hadn't managed to get the job.