Ivan's Childhood is unquestionably a remarkable film without which his other masterpieces like Stalker or Mirror would not have been possible.
Andrei Rublev is widely considered the pinnacle of Tarkovsky's achievements and an absolute classic of world cinema. In 1969, it won at the Cannes Film Festival
When Tarkovsky worked on Mirror, he was already a fully formed artist. He had developed his own unique language through which he communicated with the audience.
Unlike Solaris, where Tarkovsky retained elements that clearly linked it to science fiction, Stalker only briefly references cosmic themes.
Although Lem was largely right in his criticisms, because Tarkovsky did use his story to fulfill his own intentions, I consider Solaris to be successful film.