I am thinking to buy Honda Shine 125cc bike, is there any drawbacks in it?

The Honda Shine is a very proportionate and quality offering from HMSI. Since it is tailor made for the city, you will get Fabulous acceleration up to 60 and then you will have very slow acceleration there onwards. So for most people who need brisk acceleration in the city, it works beautifully. However if you are more highway oriented and intend to do higher speeds, you should look at the Yamaha Gladiator.