I've flew around as a pterodactyl, but my dream recall was a little bit hazy in that dream. I do remember that I was basically in that form for the whole time, but essentially I wasn't doing anything that required me to experience much different from my regular dreams, as I have flown a lot before.

To be honest, it's only difficult if you make it that way. If you can visualize yourself being a different form, and doing things, it's gonna come to you easier. For me I typically try to imagine what will happen in a dream right before it happens then make some action that would initiate the action, for example, a few nights ago I had a dream where I wanted something to come up from the ground, so I imagined what it would look like, then brought my hands up in a rising motion while I focused intently on where I wanted this object brought up from the ground, and it happened perfectly.

At least, that's how I do dream control, as for staying that shape for the entire dream... well you'll just have to practice that I'd say.