Basically, it's in the title — It works! Go play it!
Edit: If it's [i]still[/i] not working for you — that sucks. But it seems that the latest update has widely been a success according to various sites (i.e N4G, GAF, reddit, etc.) If you are having trouble finding a game after the latest up date, I suggest either trying Team Slayer as it seems to have the largest population, set-up your Xbox for DMZ host, or port forwarding.
http://forums.xbox.com/xbox_forums/xbox_support/f/9/t/214551.aspx
http://support.xbox.com/en-AU/xbox-one/networking/network-ports-used-xbox-live
I can speak for a few friends and myself in saying that search times are now that of the Halo 5 BETA (which is to say — instant). However, a problem now exists where every first game I load into crashes. I have suspicions that this is a result of being in Preview Program as I haven't heard this complaint as of yet. Either way, hopefully this will be resolved soon.
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It's been working pretty well for me. Happy to see it run a lot smoother.