The title says everything. If you want to see numerous videos of the late Alpha / early Beta of Cataclysm, head over to The Cynical Brit. Total Biscuit has put a lot of different videos for our enjoyment on his blog. You can see there long videos of the new starting zones, the two first instances and other fun.
What I will say is that the starting zones seem good, definitely better than what they were in vanilla or BC. If you have not started a character recently, try it, you'll discover that Blizzard has also included a lot of help for beginners explaining most functions of the game while you gain access to them (battleground pvp at lvl 10, dungeon grouping at 15 ...etc).
My last comment will be about the instances. They are fun and relatively difficult. I do really think that (with the addition of a way too easy and nerfed first raid) was missing in WotLK. Most new players never got any training before coming to raids and when they have to learn the most basic things (like not stand in the fire) and also have to cope with the performance pressure that raiding is, they most of the time do very bad in one way or the other. So yes to harder instances that really teach something, and I hope Blizzard won't back up on that.
See you soon for the sequel of the Healing Through series in ICC.