Yahoo! is my second favorite webmail account. I check it every few days and use it for mail I want to get eventually but don't want going to my regular inbox. I'm not a big fan of the site for a few reasons. First, it does a poor job of correctly figuring out what is spam and what e-mail I want to receive in my inbox, and the other problem I have with Yahoo mail is the amount of advertising plastered all of the web pages.
I had a yahoo that got bombarded with spam. I got a new yahoo account and only gave it to very few people. I have gotten zero for spam so far and have had it for two years. You have to be VERY selective about sharing your email address. The only spam I ended up getting was forwarded emails repeatedly from people that I asked to stop sending me that CRAP!