Search Engine Marketing Weblog: "Sphere has an advanced search algorithm that hunts out relevant high quality and timely blog postings. Sphere scours the web searching out highly relevant new content relating to your search, and filtering out spam results. Sphere is said to be a faster way to search blogs, with rich added features....Personally, I am not overly impressed with the tool. It is nice that they provide up to 7 lines of copy from the related blog in search results, but I did not find that the posting were relavant enough."

Businessweek: "...My favorite feature is the custom day search. You can monitor history with it....Somehow I published the post twice. I've fixed that. An hour and 20 minutes after posting, I check Sphere to see where it shows up in the results. It appears in the results organized by time, but not in relevance. TechCrunch, Micropersuasion and others are all viewed as highly relevant--but not mine. Why is that? Maybe the Sphere engine saw my duplicate post and figured I was less than serious. But the engine is also engineered to take longer posts more seriously, CEO Tony Conrad has told me. So... By adding this paragraph, do I rise in the relevance rankings? I'll keep an eye out."

ResearchBuzz : "And after trying out Sphere, I think I like it, but it does have some of the disadvantages of those blog search engines that index entire pages instead of just RSS feeds...My biggest problem with Sphere was the fact that it apparently indexes full sites and not RSS feeds only. This means that occasionally you'll get a result, go look at it, and see that it's on the bottom of a long blog page. Or you'll search for a blog name and find zillions of instances of it, but not as post mentions, but as inclusions on a blogroll. Setting narrow timeframes for the search results (a week or ten days) seems to tone down this problem some. "

The Social Software Blog: "Good support for RSS, results that look useful, multimedia options, AJAX, date and relevance variables.  The downsides are that there doesn't appear to be a FireFox plug-in yet, no support for tagging or other user applied metadata and a widget that only works with TypePad.  That it's not based entirely on inbound links and doesn't support tags means that the algorithm really takes a different approach."