I am enjoying it as well! I just hit Act 5. Was pretty deliberate about doing side quests for the first two acts, but then started just steam-rolling the main questline so that I could get through the storymode. I'm doing this as a sorc, and haven't felt and extreme desire to check out the other classes yet, but am excited to do so. However, I feel like there is so much left to do on my main character! I would say I'm about 15-20 hours in so far, just hit level 41 or so.