Is this a very worth while camera?

OKay so right now I have a Nikon P100, that I like, but I find the photo quality is not want I'm looking for. I just started taking a photography class and I'm using my dad's old Canon TX. Which I found that I really love using. But I can't use this all the time, as I don't have a dark room and chemicals necessary. I know someone who takes amazing photographs and found out that he uses a Canon EOS Rebel XSi SLR digital camera. I was looking online about it, and I was looking at the newer versions of the camera and came up with the Canon EOS Rebel T3i Digital SLR Camera.

Here is this link: http://www.ritzcamera.com/product/EP128951457.htm

My question is, is the camera worth the 700 some dollars and if so, which lens would be best? I would mostly be taking pictures of nature…

Or do you have any other camera recommendations?

Yes, the T3i is a great camera. In the right hands, it will produce excellent photos. If you feel like it has all the specs and features you need, go for it. Otherwise, you should consider a few other models in the same price range like the Canon T2i or Nikon D5100.

There's no best lens though.
However, here is something that should help you decide on a lens that suits your needs:

http://www.cambridgeincolour.com/...lenses.htm

Yes the Canon T3i is good camera. Since you are a beginner, I will give you my recommendations

Canon T3i, T2i, T1i, T3
Nikon D5100, D5000, D3100, D3000
Pentax KR, KX
Sony A580, A500
Olympus E-620, E-420

All of these are good cameras that perfect for the beginner who wants to learn Digital photography. They can be found from $500 to $800.In general, best camera is the one that you feel most comfortable using. I would suggest you try out each one you are interested to find the one best suited for you.

Hope this helps