If you like simple and easy to pick up word games/puzzles, Sextuple Word Challenge is definitely worth the $1.99 price tag. This game isn't complex in the slightest and it's presentation isn't what will keep you coming back to it, as it's just a bunch of blank spaces for you to fill with several combinations of the 6 letters you have at the bottom of the screen.
If you haven't played a word challenge before, think of it like scrabble without having to decide where you place your words. After awhile you run out of ideas for new words to make, so they've even thrown in a random mix function that will move your 6 letters around to spark some new ideas.
Each round is timed, but during that round you can only gain points, not lose them. Spelling a word wrong or entering a duplicate does not penalize you at all. If you get caught up on a puzzle and just can't beat it, you can press the little refresh button and depending on whether or not you have enough points, restart the game or move on to the next round.
While this game isn't as captivating as Monkey Ball or any other graphically intense game, it will suck you in. The game won't eat through your battery like most of the other iPhone games. Plus you can also pick it up and play or shut it off in a second without worrying about losing your score or dying like you would in other games. This game is definitely worth the $0.99.