Hitchhikers is one of those games at times so dastardly, so unfair, so evil, that it shouldn't be enjoyable to play. But thanks to the wonderfully enjoyable writing of Douglas Adams and Steve Meretzky, HHGTG is an enjoyable puzzle-fest.
Sure some of the puzzles take dieing and restarting to solve, others take immense amounts of obtuse logic to complete. Because of the difficulty, HHGTG is very fulfilling if you complete it. It's a must play for fans of a) Douglas Adams or b) Classic puzzle-laden Infocom IF.
Ralph is an enjoyable game. It is consistently well-written and well-implemented. Your character is thoroughly believable. The fact that you play an average, run of the mill, house dog makes the game that much more enjoyable.
My only qualm with Ralph is its shortness. There aren't any glaring bugs or typos, and the writing never loses voice or style. If you like playing a game with a non-human player character, go for it.