We can talk of this great Sri Vaishnavite Acharya only in terms of superlatives of the highest order.
Not many people are aware of the fact that, in the 4000 Divya Prabandham, not all verses are in praise of Lord Sriman Narayana. 11 pasurams are in praise of Sri Nammazhwar (composed by his disciple -Sri Madhura Kavi Azhwar). Another 108 pasurams are in praise of Sri Ramanuja. These 108 are called the "Ramanuja Nootrandhaadhi", composed by Sri Thiruvarangathu Amudhanaar. Such is the greatness of Sri Ramanuja.
Sri Ramanuja was a revolutionary - a gentle one at that. Not to be confused with extremists. He firmly established the philosophy of Sri Sampradaya, gently overwhelming other systems with his penetrating intellect, complete devotion to the Divya Dampati and Sri Vaishnavite Acharyas before him, and infinite Daya for mankind at large. Whoever opposed him was not beaten into submission, rather they were melted down by his sweetness and Saatvika nature. His spiritual power was unmatched in its greatness.
There are a lot of things remarkable and unique about this Acharya, who was at once venerable and lovable. His works are only in Sanskrit, though he was completely proficient in Tamil (perhaps, he did not want his work to be restricted by geographical boundaries). His works are all in prose form - but it is not boring, verbose prose. His prose is sweet and moving. The Saranagathi Gadya is one of the most eloquent praises of Lord Sriman Narayana ever composed.
Through his work - The Sri Bashya, he established the correctness and truth of the doctrine of Vishistadvaita, in the process systematically refuting other doctrines like Advaita. In fact his analysis is so comprehensive that, even Advaitins acknowledge that the most scientific analysis of Advaita is found in the Sri Bashya.
Adiyen Sri Ramanuja Dasan