I've had a few problems making it work like I want it to in IE when I have multiple replacements but otherwise it's fantastic. Although I can only get one replacement (all of my site's h2's) to work, my entire site just looked a whole lot better. I highly recommend it if you think you really need it. Just make sure you don't use it for substantial amounts of text.

Second that, we had tons of problems with IE and sIFR on a fairly large site - and it is only good in SMALL amounts.

We were doing the drop-down top navigation, the side navigation, footer links and some more aux links and it was slow as hell - I wouldn't recommend it if you can get by without it.