I really like it! That is, once I got over the fact that I'm getting up at 4:30AM.
Of course, I only did it twice this week - Tue and Thur. I couldn't motivate myself to get up that early for the cardio days, so I'll need to make cardio days a bit fancier.
Anyway, benefits of waking up early to workout:
1. I finally have free (and guilt free) afternoons again!

2. I barely cheated, food wise, all week. After a tough morning workout, I no longer want junk food ruining my breakfast, lunch, or dinners. I made it a point to make even my less than perfect meals have redeeming value.
3. On my non-workout days (Wed, Fri), I still woke up at my normal 6:00AM time more energized than I have been in months. This is because my Tue/Thu workouts had me pretty tired and going to bed a bit earlier, and sleeping better.
I will admit the first 5-10 minutes when I first woke up were pretty miserable. What worked for me was to sit in my chair for a few minutes and curse about how much I hate the world, go weigh myself, and then make a smoothie and drink it as I was getting prepared for the gym. (Also, I packed my bag and everything the night before.)
If you work out in the morning, I highly advise eating some sort of snack before going to the gym. You'll be more awake and have a better workout if you do.