I own a g-shock and I must say it is the best watch I ever had. It is not so much the functions, which you find on most digital watches, but the amazing durability and the trust Casio have with their amazing 5 year guarantee.
I once dropped this from my balcony on the sixth floor, almost risked injuring someone severly but amazingly, the watch didn't hit anyone and was still intact without even a scratch. I haven't dropped any other watches from that height, but I doubt they wouldn't break.
The watch itself is available in all sorts of colours, and different straps as well. The most common strap is the velcro one, but be warned, once you sweat in it, you won't be able to get rid of the stink.
The functions are the usual ones: alarm clock, stopwatch and countdown. Obviously there are the other little settings, like whether you want the "illuminator" to go on every hour or the hourly beep and so on.
The watch being very big is also good for concerts. When you enter a mush pit it acts as an amazing weapon and can inflict serious damage, if you want it to that is. I think that maybe its size is rather excessive, but then again it wouldn't be as durable but people would stop asking you whether it has an incorporated coffee machine!!
Another defect is that it doesn't really match with formal occasions, but if your a sporty person, or want to show yourself as one, there is nothing more perfect than this watch. The price is rather spiced, but its almost Christmas so you might urge yourself to spend that little bit extra . The watch is worth it. Casio definitely trust their product, if your watch breaks within 5 years, they'll give you a new one, for no additional cost, at least thats what they claim, but quite honestly I think they'll find something to charge you on.
Anyway back to the watch. Its good, if you like the style, don't stand their looking at it,
buy it.