Well, I have created one game with the DK1 and have tried the in-between-dk1-and-dk2-version at GamesCom.
I personally have had some issues with both as a consumer - I get motion sick very quickly, it seems. Apart from that, the most critical point is the resolution. The sense of immersion is really great even in with the DK1 version, but the resolution is kind of a showstopper. However, the DK2 version is already much much better in that regard, and afaik the consumer version and future devkits are supposed to continue this trend.

It's hard to recommend for or against spending the 300 dollar - I personally will not buy a devkit nor the consumer version, mainly because of the issues I have with the motion sickness, but also because for me, it's still more or less a gimmick, and I won't spend that much for a gimmick. Especially because I know enough people who will buy the consumer version, so I'll have access to it anyways.

So, to answer your question in a more compact way, I'd recommend to try it out before buying and then make a decision based on that.
Not to forget, it also depends on how games use it - apart from implementation (which is rather straightforward), it's not easy to make a game that offers an enjoyable Rift experience. First of all, the game has to run with a constant 90 frames per second with the DK2 (60 with the DK1) for minimum latency; Also, there's a lot of details to get right, like movement speed, input scheme design, etc. etc. that basically make or break a VR game. So I'd probably also recommend to wait until a few games have been released that reportedly offer a smooth, enjoyable Rift experience.