Don't get me wrong I think he is very charismatic in his roles, but I don't think he has that much range. I don't really know how to describe it but he is kind of always the "underdog-yet super smooth-attractive guy".
shareYes, he is quite good, but I think you have to watch a lot of his earlier, smaller films to be able to really appreciate it. Most of his roles since 2010 (Inception, The Dark Knight Rises, Premium Rush, Looper, The Walk, and to some extent Don Jon) haven't been that substantial or challenging from an internal, emotional-psychological standpoint and depend more on the physical, external aspects of acting (i.e., fight or stunt choreography, adapting different accents, mannerisms and appearances). JGL is a versatile actor--from action to comedy, he's reliably good--but I think his strength is the ability to go to challenging psychological places, and that requires a certain kind of space, so I'd check out:
Manic (2001)
Mysterious Skin (2004)
Brick (2005)
The Lookout (2007)
Hesher (2010)
This isn't to say I think he's been flawless, but considering that he's consistently delivered good to great performances in a versatile career, and considering the intensity and authenticity of his best moments, I still consider him among the best English-speaking actors in his age group (30s) working today.