Google syncs passwords and bookmarks, but only across their own Chrome browsers, and you can only use it in conjunction with your own (Google) account.
I tried xMarks but found it very buggy indeed, imo. Chrome works better and syncs all my bookmarks between my netbook and desktop. My husband has his own Gmail account, which means he has a separate set of bookmarks that sync between his two desktops. It is more than sufficient for us, and I asked (and got) a refund for xMarks. So, as for your question if Google sync is better than xMarks, I'd have to reluctantly say "yes".
However, LastPass runs circles around the Google password sync feature, and will be for a LONG time to come, I'm sure.
First of course there is the additional features such as secure notes - granted, Google stores credit card information as well as profiles, but I can't comment on the first - I never trusted my credit card information to them. As for the profile, in no time I ended up with hundreds of (slightly) similar profiles... Google has a lot to improve still.
Google does remember your password, but you still need to remember your username. Sometimes I use Sophia, sometimes SophiaB, or my full name, or e-mail address, sometimes I like to be slightly more incognito... LP knows it all.
There is no way you can look up your password in Google sync, and in some cases when you need to fill in your PW for additional setup (such as some sites asking you to re-enter your password when you wish to edit your profile) you still need to fill it in manually, which means you can't use a password you are not prepared to remember.
You can't generate passwords with Google.
You can't "save all entered data" such as with LastPass.
You can't view a list of saved passwords and the sites you signed up for.
You can't share a one time password with somebody.
You can't use similar sites, such as amazon.com and amazon.ca and log into both without entering your information twice.
My husband and I each have our own profile in LastPass, so that we can log into (for example) Gmail separately, however our online banking account we added to both our profiles, Once a year we are forced to change our pw, and whether he changes it or I do, it doesn't matter, we both always have accurate information.
And, last but not least, with Google sync you are not only tied to Chrome (which in my case is not a problem, I love it!) but you can't view your private information on any computer but your own system, not on your Android phone even because that uses a different browser.
In short, all Google Sync does concerning passwords is fill in your saved password on certain sites and certain conditions, but it won't take away the need to know your password, because you will find yourself having to re-enter it manually many times after all.
LP is here to stay for a long time, I'm sure of that