here's some of how i look at these kind of directories
for Ezilon, you might go to checkpagerank.net, it gives the page rank - 6; alexa rank - 4,049; whether it's listed in Dmoz - no; yahoo directory - yes (a definite plus - that's a positive Trust factor); the domain age - 9 years 7 months, since Dec 2002 (great. the directory has age, and very likely substantial authority and trust); domain history which takes you to the wayback machine and you can check it going back years how the front page has changed.
then go to majesticseo.com and register, and i always check the Historical Index as that gives me a good idea of the long term status and 'universal popularity' of a site etc: and we find out that Ezilon has 34,700 referring domains total (impressive - one of the tops of any directory i've ever checked, lots of authority factor there from all those unique domains) and had over 6,000,000 backlinks, along with 103 EDU referring domains and 11 GOV referring domains and it has a "Majestic Million position of 11,664" which even means you might get some traffic from it. you can also see other good and fun stuff like the # of referring domains to the Top Pages of the directory/website and charts on the recent backlink history
these are just two of the (free) tools that I use to check out the quality of a directory or website.
whether this is worth it for you to invest in a listing depends on your budget. but these kind of figures/stats indicate to me a top quality directory which has been around for a long time