At this point, I'm literally tired of convincing people to try the first game. If people are attracted to games driven by solid storyline and voice acting, then this is one of them. Grossly under-rated and hated by many for reasons unknown. I loved the first game and thought it was more like a Michael Mann movie than a game. I think it drew a lot of inspiration from Mann's movie, Heat (1995). Infact, David Cage would have been a perfect candidate for Lynch in the upcoming Kane & Lynch movie, which now has Jamie Foxx as Lynch, a miscast. Anyway, the game is top-notch on the dialogues. The character development and intensity is awesome. I had completed this game in a one sitting, that's how interesting it was. True it's a bit short, but it's worth it. The graphics may look dated, but don't just go by the cosmetic looks. The gameplay mechanics a very simple and basic. People have complained about shoddy controls and technical glitches, but I didn't encounter a single one during all my 3 play-throughs. It ran well on my 7900GT, as it did on my HD4850.
I have been waiting for the sequel since the first game ended. After playing the demo, it's turned out to be even more intense. You'll find that the look and feel of the game has been completely modified. It has a grittier look and more violence. So if you ask me that the first one is still worth playing, I would say, F*ck YES! It just a 3 year old game. I completed Mafia recently which is close to 8 years old. Great games deserved to be played, no matter how old they are.