I've been mulling over this for long enough, so it's time to actually write something (warning, some spoilers):

Ultimately, I think Toradora! is a good series overall but not an exceptional one. In hindsight (and after Author spurred me into rewatching the first two episodes), I feel that it had a strong beginning, a good but relatively ordinary middle, and ended very strong with a powerful ending, partly because it was willing to have its characters grow and change and partly because it is willing to be decisive. In this it managed to be that rarity, an anime show that gets much better in its final stretch (I would say the last three episodes).

One of the interesting things about Toradora! is how atypical and oddly structured it is. There are no romantic complications that show up (Ami does not count, because everyone else is oblivious), and part of its strong and fast start is how it decisively disposes of the Taiga/Yuusaku issue in the second episode. In an ordinary romcom, I would have expected at least one romantic rival and for it to take ages before Taiga approached Yuusaku.

Another thing I noticed (due to rewatching episode 1) is the difference between the narration that opens the first episode and the narration that closes the last one. Based on the final line, it seems that over the course of the show Taiga and Ryuuji have gone from thinking of love as something that is found to thinking of it as something that is created.

(This fits well with their overall growing up and especially their decisions in the final episode.)