I love my gmail as much as I love Google. Compared to Yahoo, Gmail's simple layout is just right and comfy. And I don't mind not having the blinking avatar that Yahoo mail has. In fact when I open Yahoo mail, (because I have a relatively slow PC) My avatar comes out bald and in a split second comes out normal.
The ad placements in Gmail are very beneficial. You get advertisements that are relevant to the e-mail you open. I click on the links almost everytime I open my mail. While at Yahoo, the ads are just money-maker banners.
Gmail has an added feature, 'chat on gmail'. I don't use it yet but I bet it's another good addition.
Have you ever experience opening your Gmail and it goes "GMAIL SERVER ERROR CROSS YOUR FINGERS AND TRY AGAIN" Now everytime it does that, it give me a nervous breakdown. I literally cross my fingers everytime I click on "refresh". My whole living is in my Gmail account. Miracolously, it does come back again after 15 seconds or so, after some amount of praying.
Gmail is much better, I find it's simpler to use than yahoo mail, and it loads much faster. Furthermore, if you have the inbox open the title tells you if you have new e-mails.