Take a look at the following code snippet and tell me what you think, is this a bad idea. I could use describe calls but I might hit the 100 describe call limit. I don't have anyone to bounce ideas off of at the office so I thought some of you would have some good input.

/*
  obj is a sobject from a dynamic soql call.
  fieldName is a string that can be the api name of a field on 
  obj or the api name of a field on a parent sobject of obj.
  (exp. obj could be a Contact record and field name could be 
  something like: 'Account.Name' or 'myParent__r.myGrandparent__r.myField__c')
*/
private String getFieldValue(Sobject obj, String fieldName) {
    Object fieldValue;
    if(fieldName.contains('.')) {
        for(String s : fieldName.split('\\.')) {
            try { 
                obj = obj.getSObject(s);
            } catch(system.SObjectException e) {
                fieldValue = obj.get(s);
            }	
        }
    } else {
        fieldValue = obj.get(fieldName);
    }
		
    if(fieldValue != null) {
        if(fieldValue instanceof Datetime) {
            return getFormatedDatetime( (Datetime) fieldValue);
	} else if(fieldValue instanceof String) {
            return (String) fieldValue;
	} else if ... {
             ... // and so on
        }
    }
		
    return null;
}