Me and my brother have both taken it due to penicillin allergies when we got our wisdom teeth removed.
The side effects are common to all antibiotics, not just Clindamyacin. Abdominal cramping, diarrhea, nausea, these can (AND DO) happen with just about every antibiotic out there...You can minimize the side effects by not taking it on an empty stomach and drinking lots of fluids with it.
It is also a very common topical cream for acne and also frequently used as a cream for bacterial vaginosis.