Okay, let me start by saying that guys don't get nearly enough credit.
Seriously. When it comes to sex, we really don't get the props. It's surprisingly hard work propping yourself up and doing the grunt-n-thrust, and any woman who's ever tried a strap-on for the first time will probably discover muscle aches in muscles she didn't know she had.
Now, I'm a big fan of strap-on sex. Receiving or watching (hey, I am a guy; watching two--or more!--girls get it on never gets old. I swear it's genetic.) And, fortunately, I've been graced with a number of partners who dig strap-on play too. The biggest problem, at least from a strictly physical perspective, is that it's generally not as much fun for the giver as it is for the receiver, which is why this thing exists:
This is the Tantus Feeldoe. If it doesn't look like an ordinary dildo, that's because it's not. It's the Ferrari-frikkin'-Formula-One race car of dildos. This thing has a patent on it, and seriously, who patents a dildo?
The "strapons are more fun to receive than to give" engineering challenge has been tackled before, of course. The old-fashioned double-ender was an early attempt to design around this problem, and today modern science has given us other specialized strap-ons that try to work the same way (like the Nexus and the Share, or if you're a mutant extra-terrestrial creature whose ideas of Earthly delights come from watching tentacle hentai beamed into space from Japanese network television, and perhaps had had a female vagina described to you but had never seen one up close, the Tango), but none are as successful as the Feeldoe, at least from the point of view of your humble recipient.
The Feeldoe comes in four sizes, which Tantus calls "Slim," "Original," "Stout," and "More." People who use them for girl-on-girl vaginal fun might call them "small(ish)," "medium," "large(ish)," and "large;" for teh mad analz, they might more reasonably be described as "big," "really big," "really really big," and "holy mother of God!" They're conveniently color-coded, so you can avoid those awkward after-sex "are you sure that was the size you intended to use?" conversations.
And did I mention they vibrate? Seriously. There's a cunning little slot in the base for a small but remarkably powerful little vibrating device.
Plus, silicone! You can wash it in the dishwasher! Until recently, I didn't actually know anyone who washes silicone sex toys in the dishwasher, but everything I've ever read about silicone always mentions that you can, so...you can wash it in the dishwasher! Then I spent a week with a bunch of kinky folks in a castle, and...
Yes, you really can.
I don't recommend it if your mother or your aunt Mildred lives within easy driving distance and has the habit of popping over without warning; "Hey, Mildred! Come look at what I found in the dishwasher! It's...it looks like...Oh my God!" But you can. If, y'know, that appeals to you. Or you have a dishwasher fetish. Or something.
So, yeah. Good for the giver as well as the receiver; that's the general engineering notion here. There is actually a downside (and I don't just mean with the "Holy mother of God!" model) and that's the fact that it isn't a strap-on for beginners.
Any hands-free, harness-free design, no matter how clever, takes some work to learn how to use, which is probably another of those places where we guys really don't get near enough credit. Granted, you can use this dildo with a harness; you get one of the harnesses that uses rings to hold the dildo in place, you take out the panel behind the ring, you put on the dildo, you put the harness on over it, and it ain't goin' nowhere, so you end up with the best of a harness design and the "oh my God it gets me off to give it to you!" benefits of the hands-free design, and that's all well and good.
Gets a bit spendy, though. This toy won't be the cheapest thing on your shelf to begin with (though I happen to believe it's more than worth the cost), and a high-quality harness is going to double the price, so it...
Well, now that I think about it, it's like anything else. Spend the money to do it the easy way or spend the time to learn how to do it the hard way, I suppose.
As for the rest, it's pretty much what you expect from a well-designed sex toy. Yes, awesome G-spot stimulation (for both the giver and, if the receiver is a woman, the receiver). Yes, Incredible, mind-blowing orgasms, of the kind apt if they are not well-regulated, to have you waking up some hours later with a chunk of missing time and a "what the hell just happened?" expression. The state of sex toy design being what it is, these should be baseline givens in any good toy, and the Feeldoe meets those expectations admirably.
And it has a bit of that "mad scientist's lair" look to it. I'm always partial to things that look at home in a mad scientist's lair.
I have two of these, in the "big" and "really really big" sizes. If you prefer the "holy mother of God!" size, then you're a far better man, or woman, than I.