It sounds better with really :) I really like this product.

Zoe's answer is correct, and the best option. Your first option is incorrect, because you use 'I am'. You need to follow that with an adjective. 'Like' can be an adjective, so in your sentence, 'like' becomes the same as 'similar', not the verb that you intended. So you saying that you are similar to the product, not that you prefer it! You could change your second one to make it sound natural by adding 'much'. We don't use 'very' with 'like', but we do use 'very much' with 'like' (at least in British English) ) - I very much like this product.