Opinion mining or Sentiment analysis, although being a new research field, plays an important role in computer sciences and attracts interests of academia as well as industry. In this paper, an upgrading SentiVoice - system for querying hotel service reviews via phone [10] is described. Vietnamese questions understanding task was dealt by using Definite Clause Grammar (DCG). Aspects and opinion words, which are extracted, are based on some pattern rules thanks to GATE'S JAPE. Besides, Perceptron Algorithm with Uneven Margins (PAUM) technique was applied to classify an overall review comment as positive, negative or neutral. Experiments on aspect extraction, opinion summarization on aspects and the overall sentiment of the review are showed.