If you're unsure how the supplemental draft works, here's a good explanation.
Gordon is a high-risk/high-reward pick, as he possesses the prototypical wide receiver size and skill set, but has had off-field issues.
At 6'3 224, Gordon is tough to deal with for opposing secondaries. He ran a 4.52 40-yard dash for NFL scouts at his pro day, and may be faster on the field than that time indicates. Though he barely played as a freshman, Gordon caught a solid 42 balls for 714 yards and 7 touchdowns as a sophomore.
The next year, however, Gordon was suspended for the entire 2011 season by Baylor for failing a drug test. He then decided to transfer to Utah, but before ever playing a snap, he decided he was done with school and applied for the supplemental draft.
When Cleveland selected Gordon in the second round, only one team (the Buffalo Bills) selected ahead of them. Therefore, it is quite possible that other teams put in a bid for the wide receiver. According to Tony Grossi of ESPN Cleveland, a league source projected Gordon as a top-10 overall pick in next year's draft, so the Browns may have struck gold by only having to give up their second round pick next year.
The Browns expect Gordon to pan out into a number one receiver, and they also plan on having him contribute significantly as a rookie. Gordon has the size, speed, and hands (he reportedly caught every pass at his pro day) to make an immediate impact. What he will need to work on, however, is his route running, maintaining speed out of his cuts, and his understanding of a new NFL offense. You can never be sure how long it will take to master those things.
With Gordon, the Browns have a great offensive core to build around. With Brandon Weeden at quarterback, Trent Richardson taking handoffs, and Gordon and Greg Little catching passes, the Browns very well may become a legitimate offensive threat.
Greg Little may not be a household name, but as a rookie last season he racked up 61 catches, just 4 less than rookie leader A.J. Green, who had 65.
Granted, all the hype around Gordon is based off of 42 catches during one year of college football, so he likely will take a little while to develop. However, he certainly has the tools to become a vital piece in Cleveland's young offense.
I don't have access to very much tape on Gordon, but here's a play that showcases his on-field speed, which is exceptional for a kid his size: