The Clark/Bellamy scene was good and helps us understand Bellamy a bit more. He trusted Clarke to save his people, but Clarke fucked things up by working too closely with the Grounders and then getting screwed over by Lexa
The thing is, there's no moral ambiguity to his latest atrocity to make it compelling. As the viewer we 100% know that Pike/Bellamy is in the wrong. There were never any hints of a plan for the Grounders to attack Arkadia, or any idea that the Grounders had warlike intent, or even any Grounders showing signs of aggression that could be misinterpreted as acts of war.
If there was, say, a rogue Grounder commander planning to attack Arkadia using a sneak attack of warriors who then got caught I could believe it. Pike and Bellamy would mistake the rogues for the whole group and wipe them out in retaliation. Throw in Bellamy's girlfriend dying at this point and boom, motive and ambiguity.
Meanwhile, the City of Light stuff just got really interesting. The show was missing this kind of Mt Weather mystery in its early episodes this season and it's just the kind of fuel that can keep viewers engaged (a la Flash's Zoom).