I'm just over 32,000 words, and I'm not finding it too hard right now. I have actually managed to catch up to my word target after a weekend away on a Hen Do. Not too bad, I think.
My story is a little boring, lacking in explosions and the like, but at least I have stuff planned now which should see me through to 50k.
After writing Inter Vivos though, 50,000 words seems like nothing. I don't mean in terms of effort, because it is still a big achievement to write that much, especially in such a limited time. What I mean is in terms of story developement. I've less than 20,000 words to go, and I'm starting to realise that the big things in my novel are going to have to happen soon. I had planned to kill off a minor character at 32K exactly, but I'm nowhere near that yet (about a day away in story terms). And then a major character has to die, and I've realised I'm going to be writing that in about two days time at this rate. So the whole writing process has gone so fast that it doesn't feel like it's even sunk in what has happened yet. It's like I've sleep-typed my entire story. I can type approx 2000 words an hour now so that helps and it doesn't - the story is just thoughts on a page, rather than laboured over prose. Oh well.