Yongnuo Yn-468 II i-TTL Speedlight?

I would like to get a speedlight for my Nikon D3100 and I'm really confused.
First is this a good speedlight?
Will it be fully compatible with my Nikon D3100?
Will it auto set all of the functions? (Zoom, Power, ETC)

http://www.amazon.com/...007E3PSGW/

You can get it on Amazon for not too much.
I like to do nature photography with available light. I really do not do many portraits, so I do not need the best one out there. I would like to get a Nikon one, but the only one I can afford is the SB-400.
The SB-400 does not have the functions I want like swivial and stuff.
Does the flash have to be set off by the on camera flash?
I want it to just talk to the camera. Not wait for the cameras flash then go off.
I hope I'm making sense. This the only photography question that has stumped me.
Will this flash just let me put it on the hot shoe and will set it's self up?
All I will have to do is control my cameras settings right?

Save your pennies and buy a good refurbished Nikon SB600 or SB700.It will be worth it in the long run.

Unless you are shooting a lot of events, you do not really need an electronic flash at this time.

http://shop.nikonusa.com/...D.43898300

I would ask this question again of the YN group on flickr.

Companies such as Yongnuo cash in in people such as yourself by making a cheap but skimpy product which will probably not give satisfactory service. One thing you absolutely must check is the 'trigger voltage'. If it is above 6 volts do not let that flashgun near any modern DSLR, since the higher voltage will slowly (or rapidly) ruin the circuits in the camera and thus cause a very expensive camera repair.

Never rely on such a product to perform in the way that a manufacturer's (e.g. Nikon) own product will perform.