It's pretty but I find it a bit bland.
I know lots of little boys called Theo and Theodore in the UK and Theodora seems to be rising as well.
I also dislike all of the nicknames I can think of: Thea, Dora, Dori, Teddy and Theo (I only like the two last ones on boys).
I know a lovely little girl called Theodora who gets called Theo as well as a young teen called Theodora "Teddy" who is lovely as well who made me like the name but I still can't love it.
I wouldn't find it very exciting to meet yet another Theo or Teddy or person with a Theo-name, to be honest.
It's sort of like with Alex-names. Some of them are lovely and underused yet I still can't really get excited when I meet an Alexia or Alexandria because I know so many Alexanders and Alexandras and usually everyone is just Alex.
If you love it use it. It's a classic and you can't go wrong with it. All the best wishes!