It lacks the ability to enter username and password on many sites. In particular americanexpress.com and paypal.com. I use these sites regularly so those are the ones I remember off the top of my head. There are many other sites as well. I just don't visit them as often. These sites seem to work fine with Last Pass in Chrome.
On the americanexpress site LP shows the log in and I can click on it but nothing is entered. On paypal I get no LP button in the login fields to click on. I can select paypal login from the main LP button on the top bar but nothing gets entered in the fields. The other non-working sites do the same thing.