The best starting point in deciding whether to appeal your property tax assessment or not, is to consider how closely your property resembles the other properties in the neighbourhood. If your property is quite similar in age, size, and features it is less likely that you will be successful in an appeal, than you might be if your property differs markedly from your neighbours. 

The second, key point would be whether your property has been improved or modernized and this information is unknown to the assessors, and was thus not considered in the current assessment. If this is the case, there is a very good chance that your assessment could be increased as a result of the appeal process.