I use it quite a bit (either in Ouro itself or using base crystal). For me I run all of my toons through missed content. Some I use an origin angle like my Tech Shooter Trinity Six doing Techy missions (Clockwork, Sky Raiders, Freaks, Crey), my magic users of course are pounding CoT and BP. Naturals and story based ones often hammer the Hellion/Skull/Troll/Family/Tsoo/Warrior material.
Obviously there are also the badges, even to my non-badge collectors there are some that you probably missed and have to flashback (Spelunker, Hydra Dimension) and I generally make it a point to run most of the Accomplishment Badges.
Ouro allows me to experience old content (a lot of which I can do blindfolded) with new characters whose powers and play yield a different experience (and an occasional faceplant - Negotiator mission where enemies are Orange and you are a Controller).
Teaming in Ouro is obviously less common because its like a TF and thus cannot pick up mid stream. There are players who very frequently run OG Positron and Psyche and call team forms. Occasionally someone will call a Silos (for the Jade Spider) or meet there for an SBB or something like that. Almost all of my level 50's are parked there due to my use of Flashback and ease of getting to teams running elsewhere.
Improvements. Personally I would like to see the outbound O-Portal have Skyway, Steel and Bricks added to match where people issuing core TFs are located as they do the V side.