alexpoli - That link is quite good. I'll keep it for the next time I explain how different Turkish is from European languages 
Göktürk Inscriptions are indeed very interesting, especially re how little the language has changed in 1,300 years and across two continents. I can understand that text when written in Latin alphabet and that is because many of the words are the same today, like:
Gök = Sky
Türk = Turk
Kirk = 40
... And many others are only slightly different from the words we use today, such as:
"Yiti" = yedi (Tr) = 7
"Üçün" = için (Tr) = for, because
Tengri = Tanri (Tr) = God
You might find it interesting that I wouldn't be able to understand poems written during the Ottoman Empire times as easily, if at all. That is because, as it says in that page you linked to, Ottoman Turkish and especially the "eloquent Ottoman" or "court Ottoman" in which poems were written had a lot of outside influence from Persian and Arabic.
This has led to a curious and rather poignant break from the near past - we know the history of our grandfathers but we don't know their cultural heritage, most of which we can't understand. We can't even try to understand, because it is all written in Arabic letters which we don't even know.