Well, you wouldn't notice it from looking at the blog, but I made the switch to Beta Blogger just a day ago. The link for making the transition had appeared on my Dashboard quite some time back, but I had put off doing it for fear that my template might look strange in Beta Blogger, my comments might suddenly disappear, or, worst of all, every single entry might be lost. Fortunately, none of those things happened and A Shroud of Thoughts made the transition safe and sound. In fact, the only real difference in the blog is that now I log in with my Google Account.
Beta Blogger has several new features not found in the old Blogger. Probably the most revolutionary of these is the Layouts feature. With the new Layouts feature one can simply click, drag, and drop various parts of his or her blog wherever one wants them. This allows bloggers a greater freedom in the layout of their blog. Beta Blogger also makes it easier for users to manipulate the fonts and colours on one's blog. There is a Fonts and Colours tab under Template which allows bloggers to easily change, say, the font and colour of one's headers. Basically, what these new features accomplish is that they make it easier for those who are not skilled in HTML or CSS to make their blog look the way they want it to.
Of course, one can still opt to go with a "classic template," in which case the new features of Layouts and Fonts and Colours won't be available. This is what I chose, as I really don't want to change my template. I am not sure it can be called "classic," as it is actually cobbled together from a variety of sources and my own sketchy knowledge of CSS, but at any rate it isn't compatible with the new features. That doesn't bother me at all, as I already know how to change the colours and fonts on the various elements of my blog anyhow (not that I have any intention of doing so anytime soon).
From what I have read there have been a few bugs in Beta Blogger. For a while people using Beta Blogger couldn't post comments on blogs using the old Blogger. For a while the link to a blog's comments feed wouldn't show up on blogs using Layouts (those using classic templates weren't affected), but I think this has been fixed now. And there are some blogs that simply cannot switch yet (those with over 1000 entries, mobile blogs, et. al.). Still, from what I have seen so far, most of the bugs that would affect the average blogger have been corrected. I think I can safely reassure anyone, then, who had their doubts like me that their blog would survive the transition to Beta Blogger. While I can make no guarantees, I don't think one will lose every single one of his or her entires on his or her blog.