I just got this game about two weeks ago and I have already put 30 hours into it. I've played 150 hours of FO3. I ran into my first crash just recently, it was loading Camp McCarran when I was leaving after getting the Vault 22 quest. I noticed the game slowed down and struggled with the load when I first entered the Camp, should have saved but didn't.
I turned off Save on Travel because ever since Oblivion introduced it, it has always caused me problems with strange saves that lead to awful situations. I had it on in New Vegas for a little while until I had an auto-save that was right outside a cave with 5 Deathclaws waiting to murder ED-E, Boone and myself. I quickly turned it off and have been trying to save it manually every 15 mins.
I think I am 30 mins back after the crash and have to get the Vault 22 Quest all over again. I'm liking it so far, it definitely feels like an expansion, but I loved FO3, and my friend who got it for me only payed $30, so it's perfectly fine with me. I'm playing on Hardcore Mode for my first playthrough because it's not really a first playthrough because I played so much FO3 and have lots of experience. Hardcore isn't too hard, I like to manage my inventory and keep it light in general (I sneak most of the time) so the ammo weight isn't much of an issue. Food and Water is also no problem since I like to heal with food and water anyway.
I haven't even gone into Vegas yet, I have explored the Mojave pretty extensively and there is still plenty to see around the Northern part of the map. Collecting weapons and leveling, it also helps for fast traveling to the inevitable quest that will be a part of the majority of discovered locations later.