How addicted to strategy guides are you? Do you have to have one next to you and open through your entire first playthrough and reading every page? Do you like to have it there in case you want to reference something as you play along? Do you like to play through the game once on your own and then reference the guide to see what you missed? Are you anti-strategy guides and do you like to build large bonfires with them and dance to the anti-strategy guide gods?
Personally, I like to play through a game once, then go back through a guide and see what I missed. I feel that using the guide the first time takes out all of the discovery and adventure in a game. Of course, when today's games take 100+ hours to unlock everything, it does get tempting to use the guide the first time through as two 100+ playthroughs of a game don't appeal to me as much as two 30+ hour playthroughs.