In case you did not know there is the site for rating employers: http://www.ratemyemployer.ca/ But how useful is it really for you as a potential employee? Well, from what I can tell, most of the time the ratings are generally pretty negative. This has to be taken in context, and a company that has a lot of employees but not a lot of ratings may potentially be a decent company, while a smaller company that does not have a lot of employees but a lot of negative ratings may not be very good. If you are lucky you will have a lot of comments and will be given reasons for why they were rated that way, either positive or negative. Having only one comment (positive or negative) is usually not enough information to accurately assess whether or not it was just one happy or one angry employee posting from a good or bad day.
For those of you still in school also check out http://www.ratemyprofessors.com/
Regardless, if you are really interested, it never hurts to do a little research. If you are scoping out a new job, try and check it out before you apply. See if the people are happy working there (if you can ask them), check and see if people flood out at 5:00, if there are a lot of fancy cars in the parking lot, if people are smiling or are walking zombies. What kind of stuff has the company produced, do they have a good track record of many successful products, or are they struggling? Another good indication is how much activity (new and leaving) does a company get on Linked In ? Do they have a lot of turn around, and what kind of people are they bringing in (experienced, or fresh out of school)?
It never hurts to do your homework, after all, it is your life.
Best of luck,