They're pretty cool, but there are definitely a few caveats.
One: Don't expect silence. The Iso cab will cut the room volume in half, possibly even less, but you won't be able to crank up a NMV 100-watter in an apartment. i use a Hot Plate with mine and the combination works pretty well.
Two: The frequency response is kind of weird. They tend to dampen high end and over-emphasize bass. Plan on using an EQ between the mic pre and the board (or get a mic pre with a built-in EQ).
Three: It's a pain in the ass to get a mic properly positioned in one. The gooseneck isn't very flexible. Mic positioning is still possible, but it's not exactly easy.