I just went on Saturday. It's very nice! Not as large as I thought it would be though. We got there right around 10:45 and there weren't many people around yet. Macy's was having a terrific sale and my husband got a great new pair of Timberland shoes for $49.99 (plus tax).
The food critic for the Orlando Sentinel gave the restaurant McCormick and Schmick's Seafood Restaurant a decent review. The food court didn't really sit well with him though (and I'll say that later in the day when the mall had attracted more people, the food court was pretty crowded, although the wait at each food vendor wasn't too long).
Most regular malls in the area just have wooden benches for their guests to sit in. The Mall at Millenia has provided leather stuffed seating, sofas, and interesting (contemporary looking) chairs.
We didn't venture into the other large department stores, but my husband found both "big screen TV with surround sound" stores (very nice but very $$$$!)
I think it's worth a visit! Very nice, very new, very clean. We had a wonderful time and plan to return over the next few weeks to hit the Macy's sales racks!
Have fun!