Eventually Gigablast indexed 1 billion pages which was quite an accomplishment for a small search engine at the time. Then it seemed to stall out, I’m guessing for lack of funds. The index got stale and it seemed very dormant.
I never was impressed by the engine’s ranking algorithm, it always seemed like only 50% of the results had something to do with the query. There may have been work going on behind the scenes but to the outside it didn’t look active. To their credit they didn’t give up and die like so many others.
However, in 2022 I became aware that Gigablast had improved. So sometime over the last couple of years they rolled out changes. 1. the index feels bigger, fresher, 2. the relevance of the SERP’s seemed much better. All said, much more usable.
The website still says 1 billion pages, but my guess is it’s several times that. I use it as a second or third opinion in search.
Right now I’d put it after Mojeek but ahead of the other search engines with their own index and algo. But they can’t sit still because there is a pack of newer engines right behind.