Blame the YouTube-ification of the market. At least that's what I blame it on. It seems that with iMovie '08 (and carried over into '09), Apple realized that a large segment of the home video market was mainly interested in creating short clips that they could easily share on the internet or with family members, etc. The new interface is great for being able to just drag and drop clips into a sequence, toss in some easy transition, and be done with it.
But like the OP, I miss the details and the power of iMovie HD. The learning curve was a little bit steeper, perhaps, but the pay-off was better control over the editing process.
It took me a while to get used to iMovie '09. I don't hate it as much as I used to, but it still leaves me frustrated a bit too often. I would suggest that you give it a bit of time and see if you end up liking it. If not, then go back to using iMovie HD. But it may start to grow on you a little bit.
The one thing that I really love about iMovie '09 is the way it handles your clip library. In iMovie HD, sharing clips between projects means copying them entirely. This takes time and eats up drive space quickly. With iMovie '09, all your clips are available to you for use in any and all projects you like. This is the main reason that I stopped using iMovie HD.