With Clearbit that is quite expensive when you pay monthly for it with lots of monthly requests, Sales Rocks is definitively a great alternative to it.
It's the type of tool that I was looking for a long time to replace some of my tools in my toolkit.
The tool is definitively what I could consider as "new", but at this stage, they are far more advanced than plenty of other "early" tools in the market. So, don't expect a 100% finished and polished tool, but if you expect that from any tools, you might also not have the right understanding that there's no such things as "finished". There's always something that can be improved.
So, overall, it's a great tool for data research, lead generation, prospect outreach, and I am sure that it'll do more in the future... and maybe more already, as I am still discovering new gems every time I use it.