The Hitachi has become my go-to vibrator ever since I ordered it a year ago. Be warned - this toy isn't for the faint of heart; the vibrations are strong and unrelenting, the noise isn't exactly what one would call discreet but dear gods, the orgasms are powerful. (And it happens to make a damn fine back massager for those days when your backpack is just a bit too heavy)

I love to use the Hitachi on my clit, but then again I'm the sort of girl who needs direct and insistent pressure to get off. If you're the more sensitive type - as one of my girlfriends is - you can cup your fingers over your clit and labia, lay the Hitachi's head on top, and muffle the vibrations somewhat; using your fingers also allows you to finesse the application of the vibrations to a degree. Another wonderful way to use this toy (if you haven't bought one of the attachments yet) is to insert a dildo that presses against your g-spot and hold the head of the Hitachi against the end. Inserting an egg or bullet vibrator before using the Hitachi is also a good way to leave you weak-kneed. I'm beginning to think that there's really no wrong way to use this little toy. *grin*
My male partner loves to use the Hitachi during sex - if I hold it above the pubic bone on the outside it indirectly stimulates my g-spot and seems to make a world of difference to him. (He's also used it while masturbating a few times...holding it against the back of the hand he's using to touch himself seems to distribute the vibrations quite nicely, if the noises were any indication)

While the Hitachi is my first choice for those days when you just need to get off now, it can also be used in a more sensuous manner when combined with clothespins, restraints or (my personal favourite) a spreader bar and some rope. In fact, most types of play can be enhanced with this gem of a vibrator...provided you're within adequate distance of a wall outlet; the cord length is the only downside I found with this toy.

The Hitachi is one of those toys that isn't much to look at; the head is a mildly textured plastic spheroid that reminded me of nothing more than a naked tennis ball and the shaft is unremarkable hard white plastic.
I can't imagine the texture enhancing the stimulation, as it would easily be overwhelmed by the intensity of the vibrations. (Never fear if you're looking for ribs, nubbins or protrusions - there's a Hitachi head-cover for you!) One of the best things about the materials is the easiness of cleaning - run a wet cloth over the head and you're done. I have heard tales of it being semi-porous, though, so if you're using it on multiple partners it wouldn't hurt to cover the head with a condom and change it when you switch from one partner to another.
I can honestly say that this toy would be amazing for a more advanced user as well as for an assured beginner. Beginners who are intimidated by the idea of a vibrator might be better served by passing this one up for something with less...oomph.

The Hitachi's best point when it comes to design would probably be how adept it is at passing for a generic back massager - very few people will look at this ungainly toy and imagine that it's really an orgasm-producing marvel in disguise.
It's definitely a vibrator that travels well; because it's powered from a wall outlet, there's no chance of it turning on in your bag and although it's not what I would call compact it still manages to fit in my small duffel bag rather well when I want to take it on an overnight.

As to how it worked for me...once I nestled that ungainly toy up against my clit, well, let's just say I wasn't really focusing on the aesthetics any longer.

The layout is simple - a click-toggle that goes from OFF to "LOW" to "MILDLY HYPERSONIC". I've never been able to tolerate it past "LOW" without utterly numbing my clit and associated bits, but ymmv. The vibrations are definitely focused in the head of the toy and provide direct and insistent stimulation.
The toggle is conveniently located and I've never had any trouble with it turning itself off during a wank session; my gripe is moreso with the length of the electrical cord.

When it comes to noise, though...you can hear this thing through a dorm wall loud and clear, if my hall-mates are being honest. If you need a quiet, mild sort of experience then this toy isn't for you; if, however, you're able to deal with a bit of noise (muffle-able under a pillow, with mild success)then this is a powerhouse of a vibrator that will keep you coming back.

This is easily the lowest maintenance out of all my toys - I often use it over my underwear to dampen the vibrations, so it doesn't often get dirty. When and if you manage to get this toy messy, a quick swipe with a wet cloth should easily clean off the hard plastic handle or softer head. As far as I can tell, there aren't any lube or toy incompatibilities when it comes to the Hitatchi, though if you get one of the silicone head-covers you should be sure to use a silicone-compatible lube.

When it comes to storage I simply wrap the cord around the handle and drop the Hitachi in my bedside desk. Easy, simple and there's no chance of the little bugger turning himself on when company's over.

Good heavens, it's been so long since I received mine. *thinks* If I remember right, it came in a rectangular box with some generically worded instructions - it's definitely not packaged like a sex toy in the least. The manufacturer's warning against leaving it on for too long is a bit bunk, though - I've left the blasted thing on for upwards of an hour without anything other than some mild overheating.