I'm taking advantage of the Wal-Mart free trial and am pleasantly surprised with their selection. They claim to have 13,000 titles which is comparable to NetFlix. I have been able to get several titles from them that NetFlix does not have (but have also found some titles that NetFlix has and they do not). I have also been able to get movies that have been very long wait for several months at NetFlix. All titles I have received have been widescreen.
One advantage to their service is they count two disc sets as a single rental. Most rental services make you rent each disc separately.
As for the concern, that Walmart makes you pay for discs lost in the mail, I am fairly certain this is a misunderstanding. If you look at the account history example:
http://www.walmart.com/cservice/dvdh...talhistory.gsp
you will see the customer was billed for the disc he lost and not for the one lost in the mail.