I've used google translator a few times and have been very impressd with the Chinese to English translations, but the English-Slovak one is awful!
This evening I wanted to check a sentence that a friend of mine wrote: The translation started 'Thou knowest Czech!' It seems that the people working on the Slovak version of google translator finished their work around the middle of the Nineteeth Century...

Out of curiosity, I tried English-to-Russian for some text I knew well. It did a very good job.
In the middle of the last century, a French scientist asserted that science would never be able to know what kinds of substances composed the sun and stars, because not a single flying apparatus had been able to approach the flaming hot surfaces of the heavenly bodies.
В середине прошлого века французский ученый утверждал, что наука никогда не сможет понять, какие вещества, состоящие на солнце и звезды, потому что ни один летательный аппарат был в состоянии обращаться в пылающем горячей поверхности небесных тел.
I'd always thought that Chinese (Simplified) and Chinese (Traditional) would produce the same results on Google Translate using different character forms, but in fact they don't, as translation of that same paragraph shows:
在上个世纪,法国科学家中说,科学永远不可能知道组成的太阳和星星什么样的物质,因为没有一个飞行装置已能接近火焰热表面的天体。
在中間上個世紀,法國科學家斷言,科學永遠不可能知道什麼樣的物質組成的太陽和星星,因為沒有一個飛行裝置已能接近火焰熱表面的天體。
The Vietnamese to English translations give a useful, general idea of the topic but no where near an accurate translation.

Out of curiosity, I tried English-to-Russian for some text I knew well. It did a very good job.
I'm amazed it did such a good job, especially for such a long passage.

Russian to English sucks, though
Суд счел, что преступлению бывшего майора милиции, расстрелявшего людей в супермаркете, косвенно поспособствовал министр внутренних дел Рашид Нургалиев.
The court found that the crimes of the former police major, killed people in the supermarket, indirectly contributed Interior Minister Rashid Nurgaliyev
It doesn't see active/passive constructions, word order in Russain, etc. It does a pretty good job on the phrase level, but not with sentences.
I have to agree with zhp; I tried a passage from a well known story that I read when I was in school, and it didn't do a very good job.
Рассуждая таким образом, очутилься он в одной из главных улиц Петербурга, перед домом старинной архитектуры. Улица была заставлена екипажами, кареты одна за другою катились к освещённому подъезду.
Arguing thus ochutilsya it in one of the main streets of St. Petersburg, in front of the house of ancient architecture. The street was crowded ekipazhami, coaches one after another rolled up to the lighted entrance.
I have to agree with zhp; I tried a passage from a well known story that I read when I was in school, and it didn't do a very good job.
Dunno if you typed or copied-and-pasted that passage, NA, but there are two Russian misspellings: "очутилься" should be "очутился"; and "екипажами" should be "экипажами." Since these are the very words Google translator "missed," it makes a pretty big difference.
The corrected version then:
Reasoning in this way, he found himself in one of the main streets of St. Petersburg, in front of the house of ancient architecture. The street was crowded with carriages, carriages, one after another rolled up to the lighted entrance.
Sounds pretty good, doesn't it? (I can't read Russian at all, but this almost looks like natural English.)
I'm very impressed by Google Translate. I've never had occasion to use English-Slovak, so I don't know about that, but I have sometimes used it to find translations of idiomatic Dutch expressions into English, and it is amazing at that.