反面(はんめん), a noun meaning 'the opposing side', is a construction in Japanese that appears between two phrases, to show two contrasting or opposite features of a single person or thing. This usually translates as 'while (A), (B)', 'although (A), also (B)', 'on the other hand to (A), (B)'.
Being a noun,
反面(はんめん), can be used after any word that could create a modified noun, such as verbs, い-Adjectives, な-Adjectives, or even other nouns followed by である.
都内(とない)に引(ひ)っ越(こ)して色々(いろいろ)と便利(べんり)になった反面(はんめん)、家賃(やちん)が前(まえ)住(す)んでいた所(ところ)の倍(ばい)になった。
While moving to Tokyo has made many things more convenient, the rent has doubled from where I used to live.
カリフォルニアの夏(なつ)は日本(にほん)より熱(あつ)い反面(はんめん)、湿度(しつど)が低(ひく)いので過(す)ごしやすいそうです。
Although summer in California is hotter than Japan, I heard that it is more comfortable because of the low humidity.
あの日本語(にほんご)教室(きょうしつ)の先生(せんせい)達(たち)は日本語(にほんご)を教(おし)えるのがとても上手(じょうず)な反面(はんめん)、生徒(せいと)達(たち)にはとても厳(きび)しいそうだ。
Although the teachers at that Japanese language school are very good at teaching Japanese, they are very strict with their students.
田中(たなか)くんはとても頭(あたま)のいい子(こ)である反面(はんめん)、怠(なま)け者(もの)なのでいつも先生(せんせい)に怒(おこ)られています。
Although Tanaka-kun is very smart, he is always getting scolded by the teacher because he is lazy.
Caution - Because
反面(はんめん), is used to express contradictions, it will most often describe a positive and a negative, but cannot describe a positive and another positive, or a negative and another negative.
あのパティシエが作(つく)るお菓子(おかし)はとても美味(おい)しそうに見(み)える反面(はんめん)、食(た)べてみると味(あじ)はいまいちだそうだ。
While the pastries made by that pastry chef look very tasty, the taste is not so good when you try them.
あのパティシエが作(つく)るお菓子(かし)はとても美味(おい)しそうに見(み)える反面(はんめん)、とても美味(おい)しいそうだ。
While the pastries made by that pastry chef look very tasty, apparently, they taste very good.