Regarding leaving Luke with step brother... it was mentioned in a later book that Luke suspected Obi-Wan left Luke 'in the open' for Vader to find as bait. Obi-Wan was the last fighting jedi and the only one that could have possibly finished Vader off should he show up.
I *was* spoiler free until Episode III. I did not read any material after Episode II came out, I dodged theforce.net and starwars.com for 3 years, did not watch the clone wars cartoon, and refused to read hints at what was coming out. Being surprised during this movie was a great contrast to knowing everything about I and II before it came out.
*** spoilers!
I loved the movie as a whole but there were several big items that will keep this one in third place for me (behind ESB and ANH). Lucas still added scenes that only appeal to kids, all of the R2 vs battle droid crap, what the heck, it is just an astromech droid blast it! The horrid lines the battle droids did have, they were made to be completely moronic, I want those in my army of doom! The lack of good chemistry between the actors, no good lines like in ESB and ANH. Dooku dying in the beginning, I feel it would have been much more fitting for Dooku to live to the end and Anakin having to defeat Dooku to become Palpatine's apprentice. Somewhere this movie takes place over 9 months, but we can not tell when real time has transpired.
I annoyed my friends at the theator when I was showing my pleasure of seeing Jedis die, the birth of an Empire, and Padme's death (I dispise her acting). I admit I would be an evil Jedi, why can't others!?