I LOVE oasis, it is far more user friendly than other dating sites, You don't have to worry about a witty, cool, outstanding first message, you just send them a request saying why you would like to connect. Once they Accept you, you can chat on IM or send a Message.
Also, If someone sends you a request, you can decline and give them a reason as to why, You don't have to, but you can of you want to.
The features are easy to use, You can block someone from the IM window if they get a little creepy, Lets face it, the site is free and this is the Internet, there are some bad apples on here as well. Although as far as I have seen, not HALF as many as other sites, Free, pretending to be free, or paid. But also bear in mind, this site is relatively new.
You can upload up to 20 photos, which you can make the private if you wish.
You can rule out people who speak foreign languages you cannot speak,
there is no restriction on how many carachters your "about me" bit which is handy so you can complete the profile set up, without having to think of what to write on the spot.
There is a "Seeking Criteria" and you can tweak it so that only members who fit your criteria can contact you, although at present the options are limited and vague.
There is a "I am Looking for" section where you can give a brief description of what you are looking for.
You can Like members Oasis profiles via Facebook
I have not had any dealings with the admin, as I have not had any issues with the site as yet..
Overall - Fantastic site. I just hope this one stays free!

Approximate cost: $FREE!