I've ridden with toe clips and with clipless pedals, and while toe clips are light years better than riding on flat pedals, clipless pedals still feel much more powerful. The difference is especially noticeable on hills.

I think it just takes some people longer than others to get the clipless thing down. I read here about people who have no problems at all from the very first ride. For me, it took me probably a month before I could reliably clip out when I wanted to (lots of falls and lots of fear in the meantime), and a full summer before I felt really comfortable with them. Now, it's completely automatic and I wouldn't want to be without them. I actually feel more secure and safer with my clipless pedals than I do without them.

I have average sized feet (US size 7.5) and am average size/weight. When I first got my pedals (Ultegra spd-sl), even set to the loosest tension, I found it incredibly difficult to get out of them. I actually brought my bike into the shop and asked them to make sure there was nothing wrong with the pedals or cleats (they must have thought I was ridiculous). Nope, nothing wrong with the pedals. I just didn't have the feel for doing it, it felt awkward and I was probably doing something wrong (for instance, trying to lift up while turning). It also really helps (at least in the beginning) to clip out only at the bottom of the pedal stroke.

Anyway, I now don't find it difficult to clip out at all, either on my pedals or on my boyfriend's stiffer Dura Ace pedals. Once you get the motion right, it feels a lot easier (even though the actual force you need to unclip has not changed).

So, Lisa is right that you shouldn't feel pressured to get clipless, you need to do what works for you, but I wouldn't give up quite yet.

Best of luck!