I think online reviews need to be taken with a pinch of salt. In a past life (well, about 10 12 years ago) I left university and went onto a graduate training scheme with a "well known high street bank". Whilst the job was hellish, something that still sticks with me is the idea that news of bad service spreads about ten times faster than good. You receive the service you expect, or the experience, and you are not overwhelmed to say 'yep, that was fine'. Receive good service and you might be pleased, maybe tell a friend. Have a bad experience and you want to shout it to the world in any form you can. Online holiday reviews are particularly notable for this...
It's not to say that you should ignore bad reviews, if there are lots of them, then that maybe flags something up, but personally, I wouldn't be bothered by one or two...