I for one thought that Bioshock was an excellent FPS, good story and good atmosphere throughout. The novel (at the time) weapons were fun and offered something new to set it apart from other FPS games
As far as the achievements go, if you have a guide for the collectibles you can get the full 1000 in one playthrough. Would probably take you 10hrs but don't quote me on that
Plus, if you download the free DLC you can aim to get another 100 for completing it without using 'vita chambers'. There's a handy glitch to use to avoid having to do it on "hard" which the achievement requires. Instead, you can blast through on "easy" and use the glitch at the end, that way it should take you 4hrs on a second playthrough. Not sure if all can be done on one playthrough because I had already completed it before the DLC was released.
As far as Bioshock 2 is concerned, afraid I can't give you an opinion! The multiplayer achievements were unecessary for a game like this and were an obvious 'bolt on' so I avoided it. I'm holding out for better things with Bioshock 3.
Sure you'll enjoy Bioshock when you get into the story and have fun using the 'elemental' weapons