I used the Mach 3 (and then the battery vibrating one) until recently. I just switched to an old-fashioned double-edged razor and couldn't be happier. I use a good shaving cream (That comes in a tub) and a brush, lather up, and get the best shave of my life with less irritation than I ever got using the Mach3. For the first week, I got a nick here or there but not anymore. Now I just get the closest shave ever.
Regarding blade change, I changed the old Mach3 once a week. I do the same with my double-edged blade. The difference is that with the double edged blade, each blade costs about 50 cents. With the Mach 3s, each blade was about 2.50.
Here's a recent article on shaving including product recommendations, tips for shaving, and reviews.
http://www.msnbc.msn.com/id/6886845/
Here's my razor for anyone wanting to go retro.
http://www.menessentials.com/oxid.php/sid/...3399b7.25606806
There are also some videos about shaving on youtube.