I really hate the new lava sound. It made me think I had found slimes. Plus, it is all around very annoying.
I agree, it's far too close to the slime sound. I spent half an hour last night digging through a cave because I heard slimes in the area, only to eventually find out it was a lava fall after all.
Other than that though I'm loving 1.2. I started a new map with the same seed I used for my 1.0 world, and wow is it different. The world generator sure was tweaked. The general layout of the land is the same as I had in my 1.0 map but everything is so much more interesting. The relatively flat forest island I spawned on in 1.0 is still there, same basic coastline shape, same double ravine exposed at ground level, but in 1.2 it is now an extreme mountain biome! And I'm talking mountains the likes of which we used to see in the old alpha generation. In fact all mountain biomes see to be much more awesome. Actually all biomes seem more varied and interesting.
I've started a nice base into a small cliffside with a staircase down to a huge undeground double ravine filled with lava and waterfalls. Once I get established, start a farm and animal pens for food and wool and mine up some cobble I'm going to trek to the nearby mountaintop at level 124 that overlooks the ocean and build a huge castle on it's top.
And man, I've used more iron doors so far than I have in a year in the game. I pretty much only use wooden doors now for interior doors where zombies shouldn't be able to get to. I used a wood door for my hole in the wall on my first night and was quickly reminded that zombies now gleefully bust them down. In fact I think they seek the damn door out just to pound on them for the fun of it! I love the sound they make, very intimidating.