As Sam said, it's worth updating for the extra security features. You can turn off the phishing warnings, but I have it on, and to be honest, I've never seen one. It's not that much different operationally, so you'll soon get used to it, but one thing worth mentioning is that some of the add-ons for 1.5 won't be compatible, so will also need updating. As 2.0 has been out a while now, most of the add-ons should update automatically, so not a big deal. I don't really think there's any reason not to upgrade, Dave.