What she said.
I will say that I'm quite certain, after starting knitting on New Year's Eve, that I'm going to keep knitting. I really love it! Also, I'm traveling, so I need not to be carrying five jillion sets of needles with me. So I bought interchangeables (the KnitPick/KnitPro Options -- both wood and metal, I'm afraid), because I'm going to be doing a lot of different kinds of knitting. I want to do lace, and I love mohair, and I want to use a lot of different weights of yarn -- basically I want to do everything! (In the short time I've been knitting, I've worked projects with 15 mm, 6 mm, 2.5 mm and 7 mm needles!)
If I was only going to work in a few basic gauges, I'd probably just get Addi circulars and some DPNs as I needed them and in the sizes I needed them.
Since the project I'm working up to soon calls for, let's see, five different sized circular needles with a variety of lengths, the interchangeables are coming in handy already!