From the Red Sneaker Diaries, we have this description of what it feels like for a woman to fuck another woman with a strap-on:

This was one of the first few times I fucked Anna with the feeldoe strapped on – and this time, it felt natural. Strap-on sex has a learning curve – much like any other sex act, really. The “strap-er” can’t be expected to fuck like a Casanova the first time out of the gates, but after some awkward first times, it gets easier. And after it gets easier, it starts to feel natural. When it feels natural, you’re there – no more flubs, no more hesitation, no more mistakes. Just good, hearty strap on sex

Coupling the feeldoe with a harness is truly brilliant. The feeldoe will stay in place on its own, but only with decently closed legs. This limits its usefulness. Strapped into place, its stays put – perky, firm and ready to fuck. In fact, even though the straps felt awkward at first, the fact that they allow the feeldoe to cradle so firmly into me makes me forget that they’re there. Void of distracting worries of it falling out, I am free the let the feeldoe become part of me, to become an extension of my cunt. The silicone is inert, but it allows the quivers and shakes and strokes of a fuck to channel deep within me, fueling the the burning desire of my sex.

It’s a real trip, you know, fucking a girl with a strap on. My inert cock, spreading sensation to me, elicits reactions from her. Everything is delayed, sensations conveyed by proxy through the blue silicone cock between my legs. Her body tenses under me – I see her orgasm before I feel the jolting of the feeldoe on my gspot. For the briefest of seconds, I am simply an observer – watching transfixed as her orgasm washes over her. Then, suddenly, my world is flooded with that feeling – my own thighs flutter in response as I thrust again.

(I think she’s using the word “feeldoe” in reference to this product.)