Additionally, the 4 out of 4 restriction had exemptions for NOC 0 or NOC A jobs.
But recently CIC seems to have eliminated that restriction
http://www.cic.gc.ca/english/resources/tools/temp/work/cumulative.asp
However, there is always the risk of restriction on renewal.
Also there are plenty of down sides. Try getting a mortgage or a credit card at a bank with a temp worker. As soon as they see a SIN starting with 9xx (temp resident), none of standard Canadian rules would apply to you e.g. they wont give you an unsecured credit card (unless there are very exceptional circumstances, even then, would approve very small limit).
If you are in BC, you would be liable to pay government 15% tax for purchasing a property (15% of net property value).
If you have children, you won't get child benefits for the first 1.5 years.
Your health card will always be issued till the expiry of current work permit and you probably wont get coverage during any implied status.
All in all, temp worker is not a status to be on if you wish to live here.