While Ray or Big Dan will have much more experience behind their answers, in the meantime let me offer a response based on a little experience and maybe a bit of blarney.
Gmail does have some things to help it be somewhat more secure (in my limited understanding) than, for example, Yahoo or Hotmail.
- Gmail allows for long passwords (60-characters); Hotmail only allows for 16-character passwords.
- Gmail allows for special characters (like "%," "$," "#," "&," "<," etc.) in the answers to the security question, which is used for password recovery; Hotmail does not allow special characters, thus perhaps making it just a little less "secure."
- Gmail has the option (now default) of full-time SSL/HTTPS security when using the web interface; Hotmail only got it in the last couple of years, I believe; Yahoo still does not have full-time SSL, despite tons and tons of requests for them to implement it. (What in the name of email security are they waiting for ?! )
- Gmail has two-step authentication (where a code is sent to your cell phone and you enter that code after logging in with your password, after which you are taken to your webmail); Yahoo also has introduced a beta version of this, I believe, but Hotmail only uses cell phone information for password recovery. So Gmail is a bit more proactive here, whereas Hotmail is more reactive.
All this being said, it is still a fact of life that the big email providers (esp. Yahoo, Hotmail and Gmail, and, I suppose also AOL) are also big targets for hackers, some of whom "only" want to use your account to send spam to your contacts (which is still something of a nightmare for victims of it), and others of whom want to do more damage, like erasing your mail, locking you out, sending links to porn, etc. Just run a search for "Yahoo" or "Gmail" or "Hotmail" over at YouTube and look how many results are videos purportedly demonstrating how easy it is to hack into someone's account.
That may, of course, be more hype than anything else. Actually, as I understand it, if someone has a good, long, complex password and passcode-quality answers to security questions and (in the case of Gmail) two-factor authentication set-up, hacking becomes somewhat less likely. Then all you have to worry about is Google's privacy issues.