For a long time, Potter's was the antebellum survey. There are subsequent efforts, but most of them address the subject from different angles and don't really replace The Impending Crisis. Some of that is due to changing preferences in the scholarship. Potter is an extremely traditional political historian. The characters in his story are elite white men who hold office and contention among them is the vital issue. He takes narrative cues directly from their memoirs and his story mostly takes place in Washington, with occasional ventures elsewhere. That's not wrong, exactly, but his view is so limited by that that by modern standards, TIC is a bit shallow. It's not lacking in detail -if you want to know how the Kansas-Nebraska Act passed, his section on it is great- but Black Americans appear basically as props to be discussed by white men. That's not so great. He doesn't go full-bore blundering generation, unless my memory has badly failed since I read him, but there's a strong undercurrent that the slavery question has been overinflated and while the South waged a war in slavery's defense it maybe should not have been put in that position. When secession comes up, Potter argues in defense of it as if it were merely a bloodless discussion of constitutional esoterica rather than the existential crisis that both sides agreed it presented. That's certainly an improvement over his immediate antecedents like Avery Craven, who go around declaring slavery had nothing to do with anything as they devotedly reiterate postwar Confederate propaganda. It's just well below what we'd expect today.

For a case in point, Potter is entirely dismissive of slavery's salience to events in the territory of Kansas. In this he is reflecting the then-current scholarship, which was essentially that ordinary disputes over land were inflated into an existential question of whether or not slavery would exist in the territory and this was the direct cause of the outbreak of violence among whites. There are certainly scenarios where land disputes play a role in all that: Franklin Coleman, proslavery, killed his neighbor Charles Dow, antislavery, over a disputed boundary. That the two men differed on slavery and Dow was a member of an antislavery militia and boarder with an officer in that militia certainly escalated the fall out from that on the antislavery side...but Dow was a member of that militia in part because proslavery forces had virtually a routine of violently attacking antislavery whites that they brought with them from back home. Dow may have burned out a former white colonist on that land that was proslavery. The proslavery side preferred to just straight up murder people and had the general allegiance of the territorial government that they stole fair and square through massive voter intimidation and naked fraud, hence antislavery militias for people who prefer not getting killed.

Disputes over claim boundaries and the slavery question are not nearly so easy to disentangle as Potter and his sources would like, and they are generally willing to spot the proslavery side a bit more charity than the antislavery side. Despite the proslavery side assiduously cultivating a brand of "we are actually going to murder you" while antislavery militias, until an actual shooting war breaks out, operate more in the vein of burning down the cabins of proslavery people while they are absent. Rendering the Kansas Question into a matter of mere personal gripes means, of course, that the outsiders who ginned up outrage for it must have acted cynically. To Potter, Kansas is a sideshow with delusions of grandeur. That the white political class are divided by it is a show of something approaching incompetence, rather than that they have deep disagreements over the direction the country should take with regard to stealing the lives and labor of Black Americans.

This is about where Potter has to land, though. He's a historian of the Consensus School, which argues that American politics have been characterized by a very limited disagreement over largely ancillary points. Conflicts over race, class, and so forth are ultimately not big deals to these historians. That was all perhaps persuasive in the 1950s, if you were a white elite -university professors are very much among the elite at the time- and got to decide who did and didn't count as part of the American tradition, but would not well represent any other era of the nation's past...and did a terrible job of explaining its present too.

Does all of that mean you shouldn't read him? I can only give you a committed, resolute maybe. If you want an older, nuts and bolts style approach to high politics then he's shorter than Nevins' Ordeal of the Union which has similar issues. He's also not as bad as Avery Craven and company, who are basically advocates for the Confederacy. But you could do better with more recent work. Levine's Half Slave and Half Free is an overview with more attention to social history. Varon's Disunion! is a much more sweeping treatment -her antebellum goes back to the Revolution, which is very much in accord with modern trends in scholarship- and might be the best first step. Failing that, or just wanting a much shorter read, the few chapters of Battle Cry of Freedom laying out the period from the Mexican War to 1860 also do a very good job of hitting the high points.