Gabriel can usually be pretty entertaining to watch inside the ring. He has a good paced, athletic style that usually results in some pretty fun matches; especially if he's given time to work a long match.
For me though, I don't think I'd give him a strong push as a singles wrestler. When I look at WWE's mid-card to upper mid-card picture, I see a lot of talent there ranging from Cody Rhodes, Dean Ambrose, Curtis Axel, Kofi Kingston, Antonio Cesaro, Jack Swagger, Kane, Damien Sandow, Fandango and others. Gabriel doesn't strike me as someone that WWE would want to invest a lot of time in. When it comes to charisma & personality, Gabriel is limited to his "Cape Town Werewolf" howl and he couldn't cut a decent promo if his life depended on it. In all honesty, Justin Gabriel puts me in mind of most of the wrestlers to have competed in TNA's X Division, including guys who are in it right now: he's an interchangeable high flyer people tend to forget about immediately after his match is over and would hardly be noticed if he was gone from the company tomorrow.
When it comes to a push for the guy, there might be a possibility of pushing him as a part of a tag team. He & Tyson Kidd were pretty entertaining inside the ring as a smaller, high flying babyface team. As part of a team, however, I think Gabriel could benefit more from being paired up with someone who has good promo abilities.
Overall though, as of right now, I just don't think I'd push him. There are a lot of guys on the roster right now that, from an overall perspective, bring more to the table in my eyes.