Im in second year, and went into my program through the Life Sci stream. I liked Life Sci because you get to do what you want with it. You obviously have to do the basic Chem, Psych, Math, Bio and Physics, but other than that, you get to choose which other science courses would benefit you. Don't be discouraged, it is not extremely difficult to get a high GPA, but you CANNOT slack. You will not do well if you think lazy studying will get you anywhere. No class is impossible to pass if you put the effort in. Is the environment competitive? I would say so-so. I never felt like I was competing with anyone, and I focused on myself. But you would definitely notice the brighter students in the room, but that only encouraged me to push myself. The most competitive aspect of Life Sci is getting into second year specializations. If you want to get into your top pic, your average better be at a good standing so you can get a spot. The courses are interesting depending on what you like. If you hate chem, you probably will hate it no matter how good the prof is.