I'll join my voice to those saying that pot doesn't remove your control over yourself nearly as much as alcohol.
From a standpoint of physical coordination, you have to be REALLY stoned before you start losing motor control. Like, more stoned than is even close to reasonable. It barely ever happens, in my experience. Drunk people are often liable to at least be clumsy, and sometimes be outright falling over themselves, but the only way I've seen people get that stoned is by eating too many brownies, and that generally just results in being locked to the couch anyway. You're almost certainly not going to accidentally injure yourself (and I know there are several people here who have stories about doing that while drunk, I certainly do).
A step up from simple motor control is fine-tuned coordination (like riding a bike or driving a car) and again, being stoned doesn't impair you nearly as much as being drunk. I can ride a unicycle with one foot while stoned completely out of my head, and I can barely get on the thing while drunk. I'm also OK with riding shotgun with a stoned driver ... I've been driven around by stoned friends on many occasions, and they and just about everyone else I've ever talked to about it says that being high just makes you concentrate more. Here's a video that gives a good perspective on it:
http://www.youtube.com/watch?v=xJx0GqR3P_oSomehow, though, I don't think this is necessarily what people are worried about when they talk about "losing control of themselves" ... enough people have horror stories about making huge mistakes while under the influence that any sort of inebriation or intoxication suggests to people that they might do something they will regret if they alter their mind. Clearly, saying that this will always happen is as foolish as saying that it will never happen ... but again, in my personal experience, weed doesn't impair judgment the same way alcohol does. I mean, it is capable of reducing inhibitions, in a certain way. But I wouldn't characterize it the same way. It's definitely a personal thing, so I'm not going to say anything definite, but ... well, I can't remember any time off the top of my head when I or anyone I know has looked back at a terrible decision thinking "Oh man, I can't believe I did that ... I was so stoned, I didn't know what was going on, what was I thinking?" I think it's safe to say that pot does not cloud a person's judgment to any unsettling, unsafe, or scary extent, but your mileage may vary, so it's a good idea to be in a familiar setting and around people you trust if you're going to smoke or otherwise ingest weed, at least until you're comfortable with what being stoned is like.
Basically, if you are thinking about using THC to alter your mind, here is what you can probably expect: disturbance in time perception, a higher sensitivity for the absurd, a heightened appreciation for art and music (or, to use less loaded language, a tendency to let yourself focus on a piece or art or music rather more exclusively and intently than you otherwise would ... whether this is "appreciation" obviously depends on whether or not you actually enjoy what you're paying attention to), some muddling of the thoughts (or alternately, increased clarity, depending on what you're thinking about), and some interesting sensory feelings that will almost certainly be pleasant (feeling "floaty" is common). It can act as a social lubricant and make your more talky and friendly, or it can draw you inward and just make you think a lot and not really interact with people very much ... a lot of people don't like it because they tend to react in the latter fashion, but I rather like smoking on my own and enjoying that aspect of it, especially right before bed. People also say that pot makes you paranoid, which I have only found to be true in a very small minority of situations, but it's certainly possible (especially if you're not really familiar with the drug) ... overall I'd call it a bit of a myth but every so often I find a little truth to it.
Things not to expect: blurry vision, slurred speech, poor motor control, and a hangover. You might make just as much of a fool of yourself as if you were drunk, but it'll be a much safer and friendlier foolishness (you probably won't be really offensive without realizing it, just really silly) and you'll probably be quite conscious of how silly you look and laugh along with everyone.
Maybe this will help people understand why so many folks prefer weed to alcohol. I certainly do.
