Bright Serenity:
Good question! Personally, I did acid first and enjoyed it. Here is my personal opinion on both of them(that is what you are looking for right?). Shrooms are shorter lasting, 4-6hrs for me, usually along the 4hr lines, and make me feel quite odd. I think metaphysical thoughts and see fractal/organic seeming patterns. I loose track of linear time and have trouble expressing my thoughts verbally, but what thoughts they are! The taste of shrooms isn't all that bad if you are used to eating mushrooms/tofu or if you make tea with them, or if you put them in something. Shrooms make me feel like I am becoming a plant or an ancient dinosaur, and I always feel like running around. I definitely cannot hold cognizant conversations for extended periods of time.
Acid is subtler, and takes longer to kick in(1-1.5hrs vs 15-45min) for me, and lasts along the lines of 10-12hrs. Less visuals, and more of a clean-cut, chemical feeling. I can act pretty normal on lower doses(1-2hits), and I would consider myself much more together than say a drunk person when i am tripping. In fact, one of the fun things I like to do when tripping is to watch drunk friends goof around. I like analyzing everthing(especially social interactions) when tripping. Visuals are mild, unless potentiated with weed and include patterns that constantly move(I stared at a wall for a couple hours last time and watched it flow like water). I feel like I am becoming a machine when I trip.
Both are fun and interesting. I have known shrooms to be more tried by people who aren't into psychedelics(a lot of people who drink and smoke weed where I am from try shrooms as taste of the psychedelic world). Definitely plan ahead timewise, because acid will make it impossible to sleep for 10-12hrs, whereas shrooms you can get to sleep in 6-8hrs. Definitely do them in safe and fun environments, and have a trusted pal/sitter/experienced tripper along for the ride. Another thing is that shrooms sometimes make me feel sick like I have a fever, whereas acid makes me feel like I am composed of pixels(kinda sickly) later on at the end of the trip. Some people get headaches the next day from shrooms, I have only had that once, whereas I can stay up all night on acid and then just feel strung out from staying up the next day. So yeah, lots of considerations to think about. Have fun, be safe

. (And take everyone's opinions as subjective information not objective, come to your own conclusions)
edit: the only method i have injested psylocin/psylocybin is in p. cubensis, and I have only have acid in liquid form dropped onto gum/candy/sugarcubes. I would definitely suggest making sure someone else has tried the same batches you use so you can know the relative strength. You won't get strychnine, don't worry, but acid might be bunk, and make sure your shrooms are dry, I have known of at least one bad experience someone had from buying wet shrooms from someone they don't know. Feeling like you have lockjaw and having trouble breathing isn't the funnest experience ever.
[ 15 May 2002: Message edited by: yucatanboy ]