The weakness of the power ring is that it has a finite charge.
I don't read Green Lantern anymore because the stories are either boring, or they don't make sense, or both, plus the editors and writers have a habit of burying my favorite character while focusing on characters I either don't like or don't care about. The franchise is currently cluttered with characters it can't properly facilitate. At least not all at once. Also, I'm tired of the events and lack of character development and proper, substantial relationship building. Plus, I dislike the whole emotional spectrum. I think it's an extremely hokey idea, and the stories tend to revolve around it a lot.
As for the constructs, they're okay, especially if used in moderation. I do think regular beams and bubbles do have their place, too.