Definitely Worth the Cash
I'd agonised about buying one of these for a while after reading mixed reviews, but when I started getting pelvic pain and I kept waking up laid on my back (uncomfortable!) I decided to just bite the bullet and get one.
Best thing I did!
From the first night I noticed a difference in my comfort levels. Previously I'd been using a standard 'V' shaped pillow, which was ok for a while, but by 21 weeks I was starting to need more support. I found that this does help you to stay asleep on your left side, because it sort of hugs you. The back support is great and feels lovely in the small of your back; this is probably what keeps you on your left most of all. The 'sausage' like bit that goes between your legs is firm enough that it doesn't really squash down too much when you've got your legs around it, but it's thin enough so that you can move your legs if you need to so you don't get cramp. The part where your bump is meant to rest isn't really relevant to me at the moment as bump isn't huge, but I think it will come in handy, and until then I can just hug that part of the pillow!