Personally, I'm a fan. It has multiple uses - can go in intake, oil or gas tank... I use it in the gas tank about every oil change - and have previously "seafoamed the intake" of previous vehicles. I can also be used several miles before an oil change to help clean up the engine internals (I've not done this, however).
I've not examined the intake before and after, but my seat-of-the-pants-ometer tells me that the times I did use it, there was some benefit.
My local Andersons General Store stocks cans for like, $6 or $7 regular price. Most other places are $8.99.