Milwaukee Job

Hi,
I'm currently working for a hospital within Aurora Health Care. I have been offered employment with Wheaton, at St. Francis hospital. I'm a bit on the wire as to what I should do. I would love the unit @ Francis however I'am reluctant because I know they are union and I have never working for a union before. Also, I dont know what their benefits are like in comparison to Aurora. If anyone as working for St. Francis let me know how you liked it. Info is appreciated!