My wife and I stayed in Samsara in Dec 2009 and really enjoyed it. I will provide you with the pros and cons from our perspective:
Pros:
Phenomenal views
Open villa
Stereo system piped in throughout villa and can plug in your own iPod
Infinity pool
Just down the street from Le Ti
Power sunshade that comes down in the evening in front of dining table (sunsets can get pretty hot)
Cons:
Mosquitos since it is open
Very little breeze
The main living area can get pretty warm during the sunsets, which can be uncomfortable at times
Bed is very hard (we were very surprised by this and we were told we were the first to comment on this. To be fair, the last villa we stayed in while on the island had a similar style/feel bed. We have a memory bed at home and could just be used to that.)
To address your question about the security, my wife and I never felt unsafe in the villa or anywhere in the vicinity (or entire island for that matter). Even though the villa is open, there is a door at the entrance that can be locked. In addition, we always kept the bedroom door locked (where you would have all your valuables locked up and where the safe is). I will point out, however, that the walls surrounding the villa at the main entrance can be climbed. I know this as I had to boost my wife over the wall....which was proceeded by an eventful evening out in which we lost our keys to the car, hitched a ride home from a complete stranger, and watched the sun rise with the mosquitos in the living area since our bedroom door was locked... as we waited for someone to come by with another set of house keys and car keys. If someone were to climb the walls, they would basically only have access to the furniture. If they wanted to get to your personal property, they would have to break the bedroom door down.
The other side of the hill does get incredible breezes, but at the expense of losing the sunsets.
Again - this is just our perspective and our must haves were sunsets and infinity pool.
The attached photos should give you an idea of what it is like from the street, sunsets, amazing views and that sunshade (which definitely comes in handy in the evenings if you are eating at the table).