I have it. Been working through campaign mode. Haven't encountered anything that needed more than a single try so far, but I hear it gets pretty tough near the end.
It has too many new items to list. I'd say it has about twice the weapons & tools that the expanded PSN release of the first XBLA game had. The drill is back but I haven't came across a bungee cord yet (Doesn't mean its not there, I haven't seen a few things yet). Its expanded in about every way you can imagine. New game modes, a lot more variety in landscapes (Vertical landscapes are back), etc.
Other than some bugs that I've seen widely reported (That haven't affected me yet) and the backwards jump being broken (Works about 50% of the time, unlike past Worms titles where there was never a question when you did it of your Worm doing what you want) leading to making yourself looking like a idiot as your Worm leaps into the water rather than backwards jump like you wanted, I'm pretty pleased.
Once they patch the jumping to fix whatever is causing that problem that I'm encountering and I'm seeing mentioned widely (So its not just me), I'll be very satisfied with it.
If anyone wants to play, send me a friends request. I might not be wearing my headset (I'm not much into voice chat on XBL), but it will be fun none the less.