We went last summer (free admission for military families--thanks Anheuser Busch!). I was very pleasantly surprised by how gorgeous the park was. The landscaping was absolutely lovely. Everything seemed very clean and organized, and the shops were fantastic. There were lots of nice touches--swings and benches to sit on to watch the rollercoasters, the clydesdale barn for great horse viewing, a high-energy music-and-dance show out in the open where you could just walk by and watch for a few minutes, etc. We ate at the BBQ place (can't remember the name)--TONS of good food for a reasonable price. I'm not a big coaster fan but DH rode Alpengeist and a couple others and declared that they were fantastic. I especially enjoyed the train ride around the park and also the wolf demonstration and the sky ride.
Like someone else said, be prepared for the hills--I wasn't! Bad shin splints the next day, ouch!. Also, I'm not sure if you're going with small children or not, but we were disappointed by the lack of "family" rides--with a few exceptions the rides were either "big" rides (rollercoasters, etc. with height restrictions) or "kiddie" rides (tiny carnival-style rides that really don't accommodate adults). We sorely missed the many, many rides at WDW that our whole family (DH and me plus DS 3 and DS 1) could ride together.
One other thing I might mention is that beer is everywhere (it is Busch Gardens, after all). We went on a busy day and by the end of the day there were quite a few people who were getting loud and obnoxious from too much to drink. DH (who enjoyed the Beer School but stuck to Cokes after that) almost socked one guy who was making loud comments about my chest. I'm sure it's not like that there every day but that did sour our day a bit.
Overall I think Busch Gardens is great! We will probably go again this spring. I hope you'll have a wonderful trip--enjoy!