Billy Hamilton was drafted in the 2nd round of the 2009 draft by the Cincinnati Reds. According to Baseball America, he was the 48th best prospect in all of baseball coming into the year. I saw him play against the San Jose Giants on May 31st 2012.
The first question was his defense. Hamilton is a shortstop, but there have been tons of questions about his defensive play, and it has been speculated that he will be moved to center field to better suit his speed (more on that later). In what I saw, he handled everything just fine at shortstop. He did fine with both popups, and grounders. He got good jumps on balls, and his range was pretty good. There were no glaring holes in his defensive game that I saw, but it is much harder to scout one game defensively than it is offensively. You just don't always get to see them in action. If there have been multiple scouts and writers that question his defense, it is hard to overrule them just from what I saw. It could also be argued that even if he becomes a good shortstop, that there may be more value in him playing center.
Now for offense, Hamilton leads off for his team, the Bakersfield Blaze, most likely because of his speed. He showed off that speed in his first plate appearance, when he bunted in a 1-1 count. He bunted to the pitcher, but the pitcher made a throwing error, and Hamilton made it to 2nd base. Speed is Hamilton's game, as he is rated as having 80 speed on the 20-80 scale by everyone. He already has 222 steals in 297 professional games in his career. Baseball Cube rates his speed at 99 out of 100, and his speed scores have been 8.9, 9.6, 9.2, and 9.5. In his 2nd at-bat, he hit a first pitch low fastball up the middle for a single. After several pickoff moves that weren't close, he stole on a 1-1 count. In his 3rd, he took a high fastball, then popped a low middle fastball up to center field. In at-bat 4, a first pitch down the middle was fouled back, and then he popped out to first base. He was intentionally walked and scored in his next at-bat (it was a traditional intentionally walk situation). His next at-bat, he took 2 pitches to get to 1-1 before hitting a pitch right down the middle for a single. A walk brought him to 2nd base, and then in a bizarre play, the catcher picked off the runner behind him and he took 3rd. It did not technically count as a steal. His next at-bat was in the 12th inning of the game, and he chased and missed breaking balls to get to 1-2 before hitting a grounder for a fielder's choice. Naturally, he stole second. I thought he showed a decent approach at the plate (the last at-bat being more of an exception) and good contact skills. With that speed, striking out is an utter failure. So far in the minors, he has struck out 20.6 % of the time, way too much. Hamilton is far from polished at the plate, and will be eaten up alive by advanced level pitching (he is currently in High A) if he doesn't continue to progress. With his speed, he also needs to be a line drive/ground-ball hitter. While his ground-ball % has stayed at just shy of 50%, his line drive rates have been pretty low. Weak popups are an absolute waste, especially for a guy who didn't look like he had much power (stats also support this, as he has just 6 professional homers and .386 SLG. Baseball Cube rates his power at just 29). His walk rates have increased as things have gone along, and like I said, he looks like he has a decent approach, but those 2 pretty weak pop-ups were pretty frustrating. The speed is great, and he has some tools, but his overall game, both defensively and offensively needs a lot of polish before Hamilton becomes anything more than a guy that stole a lot of bases.