How accurate is google translate?

Teachers say its inaccurate, but I think it is.

you are using but wrong, but implies you disagree with that, you should have said you as well agree

It's not helpful at all. If you screw a long sentence together and try to translate it, it's gonna be pretty bad. It's inconsistent and should only be used for sentences and small words.

Even then, sometimes it isn't good. It will get you the general concept, but not the little things that make a differencd. It will miss key conjunctions and put words that are more complex than you are learning. For single words, just use Word Reference. It gives more accurate word choices. For verbs, it helps you conjugate verbs to the correct form. It's just up to you to know when to use them. Way better than a type in Google Translate 

This is coming from someone who's taken Spanish for 9-10 years, and has a seal of bi-literacy in Spanish

Google Translate's database isn't sophisticated enough to reproduce the nuances between languages. This is especially true, at least in my experience, when one attempts to translate an oriental language to a romance or germanic language. For example, Japanese, a language with which I'm fascinated, has characters for feelings, not necessarily words or an alphabet. The romance, to use another example, languages feminize many of its words. While I wouldn't go as far as to say it's "inaccurate," I would agree somewhat with SupaDudz that Google Translate is perhaps better used for small sentences and words.

Define accurate.

If your "accurate" is "borderline at least get an idea of what it is", then yes.

If your "accurate" is "word by word, accurate feelings, accurate tones, accurate everything", then no.

If your "accurate" is "whipped cream on overcooked eggs", then WTF???

The thing you have to understand about Translating from one language to another is that all languages don't have a word to match all words in English verbatim. When something is Translated the translation is at best trying to get to the substance of what is being said. There is no such thing as verbatim translation. Context is often lost when something is translated. What they say in their language translated into English can be very different and vise versa. The biggest problem with English is that there are so many words that sound the same or are spelled the same or spelled completely different but have the same meaning but have completely different meanings when put into context. Without a real person who speaks both languages to translate for you. you will get a lot of translations that don't make any sense. The biggest down fall of computer translation is context, it cant know what that is. It is limited to the words that have the same basic meaning 

For example" Auto, Automobile, car, Truck, hatchback, station wagon, Jeep, Ford, Chevy, Dodge etc. all these words basically describe a car. When translated to Swedish for instance there is only one word for all of them "Bil"  So you see there are many English words words that describe a car  that can be translated incorrectly without proper context. The same goes for all languages.  

Here is a perfect example of something being lost in Translation:

"I have a Dodge Viper" If you speak English you know this is a car

Translated into another language that could mean you jumped out of the way of a snake