I haven't read much about the Union soldiers from Fort Sumner, but the fort's commander, Major Robert Anderson, is someone we know a fair bit about. He was a loyal Unionist, but was originally from Kentucky (and was himself a slaveowner at one time). A West Point graduate with a deep military and political pedigree from his parents, Anderson moved up the ladder in military circles due to his distinguished service as well as his connections.

By all accounts, both contemporary and historical, he handled himself well during the whole Fort Sumner crisis. He kept his men safe, and never forced Lincoln's hand politically with his actions or statements. Barring what you might call a "diplomatic" solution, the surrender of the installation was essentially a foregone conclusion once Fort Moultrie was abandoned, so no one held it against Anderson when he surrendered on April 13th.

Anderson returned to the north a hero, got a promotion to Brigadier General, and led a rally celebration in New York City that was the largest the country had ever seen up to that time. Anderson went on a very successful recruiting tour after that. So to answer OP's question, no: he wasn't heckled. He eventually got a command in Kentucky, a crucial border state early in the Civil War, where his status as a native Kentuckian was meant to bolster local pride and keep it aligned with the Union.

There are some questions about why he stepped down from that position (head of the Department of Kentucky, later Cumberland). The word at the time was that Anderson's health, always a bit fragile, had begun to fail him. He had received wounds during the war with Mexico that plagued him all his life, and by late-1861, when he stepped down, he seemed older than his age (mid-50s) suggested. He lived another ten years, and never really suffered any negative reappraisal either personally or militarily. He was seen as a hero immediately after Fort Sumner, and that never really changed (even if his overall contribution to the larger war effort was relatively small).

[Source: James McPherson, "Battle Cry of Freedom"; Bruce Catton, "Grant Moves South"]

The other poster covered Anderson, so I will cover a bit of the rest.

The officers and men were treated well in the north and were treated as heroes after they were returned. You have to understand the mindset of the time. Yes, they lost, but they fought. Sumter was far from the first confrontation between the southern states and later CSA against the United States.

In Charleston, Anderson had moved all the US army personnel to Fort Sumter in late 1860, immediately followed by the South Carolina militia seizing Forts Moultrie, Johnson, and Pinckney as well as the federal arsenal in Charleston.

Total Seized US assets: 4

Immediately after this, Louisiana, Georgia, Florida, and Mississippi followed suit.

Louisiana seized the Baton Rouge federal arsenal and barracks, Forts Jackson and St Philip on the Mississippi, Fort Livingston, Fort Macomb, and Fort Pike. They also seized the US mint and US army's quartermaster supplies.

Total seized US assets: 13

Georgia seized the federal arsenal at Augusta and Fort Pulaski.

Total seized US assets: 15

Alabama seized the federal arsenal at Mount Vernon, Forts Morgan and Gaines, and the fort under construction on Ship Island.

Total Seized US assets: 19

Florida is another mess. Florida militia seized the arsenal at Appalachicola. Forts Marion and Clinch. But this is where it gets interesting in that the US did respond in Florida to the threat. The US army garrisoned Forts Taylor and Jefferson. A mirrored situation to the one in Charleston SC occurred in Pensacola where the US army abandoned Forts McRee and Barrancas withdrawing to Fort Pickens. The Florida militia then seized Forts McRee and Barrancas as well as the separate Barrancas barracks and the US navy yard.

Total Seized US assets: 26. 400+ POWs.

Arkansas seized the federal arsenal in early February 1861,

Total Seized US assets: 27. 400+ POWs.

Texas seized the entire Department of Texas.

Total Seized US assets: 40+. 2700+ POWs.

I have skipped over the seizure of a number of US revenue cutters (the precursor to the US Coast Guard) as well as steam powered frigates, like the USS Fulton that was at the US navy yard in Pensacola. These seizures all occurred prior to Lincoln being sworn into office.

By the time Sumter happened, the pro-union supporters in the north were desperate for someone to fight back and not surrender without a fight. The men were treated as heroes by both sides. Most of the officers were rapidly promoted. One officer, Richard K Meade Jr did resign from the US army upon his return to the north, then switches sides and fought for the CSA until he was killed.

The rest of the officer corps at Fort Sumter were engaged in many of the campaigns of the war as brig or major generals. Some were fair commanders. Some made excellent engineers, but fairly bad combat commanders.