Once you get the hang of it, it's great. You can do stuff no other site can do. This really asks for some kind of query language. Or maybe there is one?
Both Momondo and Google Flights are decent alternatives for finding good flights, although Hipmunk’s visualization feature is better than both.
Momondo had to monetize a little in the past year, and now includes a little bit of referral spam, but still produces good results, their sort by “best” feature is usually helpful!
Hi, I am one of the founders of Trabber, an independent travel metasearch website that we started back in 2005. You probably don't know about us because we are not very well known outside of Spain, where we started and are based, and because we are small and not linked to OTAs or travel groups. I would be very happy to get your feedback, thanks! https://www.trabber.com