The "hardness" is more of a training you how to play the game. If you played old school games, it shouldn't get to you that much, today's gamers are just used to be the PvE aspects of a game being very doable. The game allows you to summon other players who are offering to help (that's part of the multiplayer aspect of the game), so if a particular boss is giving you problems, you can find a player willing to help you.
If you have a PS3, you can pick up Dark Souls cheap and try that before deciding if you want to do DS3. Playing Dark Souls for the first time was the one of the truly mind blowing experiences in gaming I've ever had.