The MAMMA MIA! Soundtrack is great. The CD is all fluff and fun, with great vocals, including the surprising Meryl Streep and the outstanding Amanda Seyfried.
The only objectionable content are some innuendos that are light and non-graphic, but are used several times. They detail them in the CommonSemse review.
It's great for all. You can pass over some of the more innuendo-heavy songs for little kids, but they will love the catchy tunes and irresistible lyrics.