Theres one good thing about the straight talk s2. GSM...meaning its somehow unlockable if you ever decided to take it to another gsm carrier.
I myself couldnt justify paying $350 for a phone though, but for the price it isnt too bad. All of the galaxy series phones have been nothing less than stellar. Ive owned the gs1 and gs2 and loved them both.
Good luck with the gs2 if you decide to purchase it