Before the D3100 I was a DSLR virgin, and this review is aimed at people who, like me 4 months ago, are sceptical about spending so much on a camera.
First the positives - I have found the D3100 easy to use and yet the photos it produces are far better than those I was able to take with my compact camera (my photos look like they were taken by a professional!). Where it really outperforms my compact is indoors. I have used my D3100 at home, restaurants and in a church without needing to use a flash and the results are amazing. This is particularly important for me, as I take alot of photos of my 8 month old son (I didn't buy the DSLR until he was 3 months old, and I really regret it, as the compact camera photos look rubbish in comparison!). We even took a photo of him sleeping in a dark room and were amazed by the amount of light the camera 'found.'
Now the negatives - It is more expensive than a compact camera. I still think it is worth it, but it is alot of money. It is also not as portable as a compact camera, which means that it is not ideal for parties, skiing, etc. We have kept our compact camera for those sorts of things (although we did take the DSLR up skiing for a 'photo day').
This is my first DSLR and before I bought it I had seen many of my friends buying them and thought, "What a waste of money." Having decided to see what the fuss is all about, I'm so glad I did, and I can't believe I put it off for so long. If you don't own a DSLR and are looking for a simple, good quality, entry level DSLR then I would recommend the D3100 (as a beginner myself). If you aren't sure if it is worth it - it is, it really REALLY is.