Season 5 also has the Bashir Changeling performing the lion's share of Bashir's most important surgeries, doing brain surgery on Sisko and delivering Kira's/the O'Briens' baby.
I think Season 5 gets overlooked a lot because the war-lovers love Season 6 & 7 whereas the war-haters like the first half of the series (Seasons 1-4). Season 5 is the transition between the two, that calm before the storm/war (kind of like how from Oct 1939- April 1940, there was no major movements in WWII, it was just this uneasy calm everyone knew was going to break into all hell at some point). It's before the war really ramped out and broke out but it's after the early mystery and the cold war/diversionary wars with the Dominion so for neither bloc is it fully in the era of DS9 they like the most.
Season 5 has some of the series' strongest episodes:
"Apocalypse Rising", "The Ship", "Trials and Tribble-ations", the Purgatory/Inferno 2-parter, "Children of Time", "Call to Arms".
and a few interesting entries:
"The Ascent" (one of the more interesting location shoots for DS9 besides the 128 degree hell of "Rocks and Shoals"), "Things Past", the 2 Sisko/Eddington episodes, the big Bashir revelation episode
and of course some of the worst episodes of the series:
"Let He Who is Without Sin...", "Ferengi Love Songs"