Since the advent of the Great Kerfuffle, I've been trying out several sites. Here's my initial impressions. Booklikes has a great GR import feature and is terrific for backing up. They are very responsive to questions and are working hard to become a real competitor to GR. The site has much more of a bloggy feel to it which can sometimes obscure reviews and book info although you can limit your view to just reviews. Not for those who really get off on editing bibliographic data. Customization is possible but hardly easy except for the techies. Synchronicity to GR is what makes the site fascinating. Works really well and you can have all your reviews, etc. ported immediately to GR.
The LibraryThing is more for hardcore librarians and is very sophisticated in the software's ability to manipulate bibliographic information. Changing covers is a blast. I haven't been on long enough to see what the social aspect is like, but then it took six years on GR to accumulate a set of friends I enjoy. The import from GR was really quite easy although the import file size is limited to 2 MB so I had to split my 4 MB GR download into 3 files in Excel - easy enough to do - to get them to import. I had one minor glitch, emailed support, and it was fixed in just a few minutes. LibraryThing would be the preference if your only interest is in backing up what you have on GR. They have a very large database, definitely a plus, something Booklikes has yet to accumulate but will soon, I'm sure. For some reason, it has kind of a DOS feel for me, but then, I'm old. LibraryThing is not free ($25 for lifetime unlimited use or $10 per year.) But that's a good thing as it provides a measure of financial independence lacking at the other sites and offers stability. I like it - didn't at first, but do now.
And whither Shelfari? I've been cross-posting there for years, but frankly, it's a bit boring. No way to import from GR that I know of although anecdotal evidence suggests it is possible but doesn't bring along reviews (so why would anyone want to do that?) My guess is that with Amazon's purchase of GR, Shelfari will die a slow death or users will be exported to GR.
I would LOVE to see a study showing how much overlap there might be among power users among the major sites. Cross-posted all over the place. :)
I must congratulate GR for getting me out and about and checking out some other sites. In the long run, I doubt anything will be different over there, after all, they do have a good site. Now if we could only do something about STGRB who about as cranky and adolescent a bunch of people I have ever seen.