I decided to purchase the game . . $5 is a fair price. I didn't buy it because of the amount of personal info they wanted. Name, address, phone number and email address? . . . its just a one time five dollar game purchase. My first thought was they are selling the data . . maybe not. Anyway, all I need is more spam, junk mail and after six calls so I didn't buy it. I wasn't motivated enough to find out if the input was required.

I'm talking about piracy in general. Was the demo available before the release anyway? I personally rarely download demos - I get the full game, downloaded, and if I enjoy it, I buy it and keep on playing. A demo just adds more crap to my system.

Most games have no demo available let alone at release date. Pirated versions appear at the same time as the games go to stores.
About the games I enjoyed and didn't buy: I can enjoy certain games but feel they're not worth the full price and wait till they drop in price before snapping them up. Games like Alpha Protocol and Singularity which are on my "below £15 = buying" list. Heck, for me the age of a game doesn't matter - the quality does. There's a reason I got 80+ games on GOG after all. I pay what I feel a game is worth basically.

Did you ever find a game worth more than is was initially priced or was it always less? :)

I used to follow a similar system, but found that it favored multiplayer gaming and did against some really good games.
As an example, Arkham Asylum. I bought that brand new and do not regret it. Amazing game, well worth every penny. But the replay value is a bit low, after you have done a 100% run (gotten every clue and caught the Riddler and the like). I will probably play it again eventually (likely the month before Arkham City ;p), but if I were to have gone by the metric of "if I like it, I buy it", I would be hard-pressed to recommend a purchase.
Same thing with Dragon Age, but for a different reason. I love that game, and there is an amazing amount of replay. But it is very draining. It is a very long game. So, after playing it, by the metric of "if I enjoyed it, I buy it", it might get skewed by "Well, I can just wait until I see it on sale" and the like.
However, multiplayer oriented games and shorter games ARE favored by that system. Max Payne 2 (amazing game) is pretty short, and I replay it every few months. So I would instantly buy that at 50 bucks (probably even now :p). But, as a result of favoring shorter, more action-oriented games, we have gotten to the point where the standard game length for anything other than an FPS is 6-10 hours.
So that is why I pretty much buy all my games these days, even if it is a risk. Obviously I try to read a few reviews from sources I trust and play a demo (if available). And I always at least try and watch a trailer. But sometimes, you just have to take a risk.

In my case, I just watch the previews here and there, then read the reviews when the game comes out. If it still sounds like it's a good game and I have the time, then I buy it. It's actually quite rare for me to end up buying a game that I don't like. I've played thousands with similar enough gameplay to aid me along with the reviews and what people are saying on forums. So no, I don't find that I need to download games to preview them. Maybe I'm just very good at gauging what I will like. The fact that I enjoy most genres, and that there's plenty of good titles to choose from doesn't hurt.
However, in the case of an excellent, yet extremely buggy game, I suppose that downloading could be helpful, and also allow one to see if the fan patches (if any) work their magic. (Vampire: The Masquerade - Bloodlines comes to mind)

I have such a backlog of games that I don't need to try out very much stuff on release day. I find, however, that demos rarely get updated as the game gets patched. Also, I don't think it's an issue with this game, but I'll rarely try demos from big commercial games, they include Starforce and SecuROM just like the released version. It's pretty easy to screw up your comp.

For me its the same. Since I can also wait some months after the initial release before I must have a game/ have some free time I can easily make sure, it has good reviews, is bug free (read in the forums, look out for patches) and has maybe lower price too. So the risk of an actual bad deal is really small. Just recently bought HOMM5Gold for 10€=13$. And just now, bought machinarium for my girlfriend for the amnesty price. She is into adventures and since it has such a high rating. Even didn't try out the demo. Although I like that there are demos, I maybe tried two or three in the last years only. They in general did not hurt the system (came with uninstallers) and also without any DRM. Demos are freely copyable, so there is no reason for Starforce, SecuRom??

Yeah, with the extensive previews, videos, walkthroughs and developer histories available at a moment's notice online the whole "pirate to demo" thing is rather silly. I'm not saying it doesn't inform you more, it does, I am just saying it is not necessary to know if you will like the game.
I never pirate to try and have only regretted one game purchase over the last few years, Star Trek Online, and I only bought that because I'm an idiot fanboy.

hahaaaahhhhhhhhhhhh :P sorry... just felt someone should laugh at you for that :P

I fully deserve it, laugh away. I knew it would be crap and bought it anyway. I even got the collector's edition.

I have to admit, I also had to smile when I red this. :)

FYI the sale has been extended to the 16th.
http://machinarium.net/blog/

More than 17,000 legal copies have been sold during the sale so far, according to the developer.