The closest translation I could think of is something like these. It's a more passive expression compared to its English counterpart, and probably less frequent to come up in conversations. Depends on context, of course. Nagagandahan ako sa dokyumentaryong ito. I find this documentary interesting/good. Nababaitan ako sa kanya. I find him/her nice.

Using I find it~ is stating your observation on something or someone you can say that in different ways: I find this documentary interesting (or: I find it interesting) interesting here means you like it, it excites you, it gets youre attention, your interest: kawili-wili, pagkagiliw, pagkagusto, interes or interesado (1) Ang dokumentaryong ito ay kagiliw-giliw. (2) Ito ay kawili-wili. (3) Interesado ako sa dokumentaryong ito. Again, all of these are bae from your obsrvation, so you can also add i think o "sa tingin ko" when you you mean it to a person like your sentence: I find this girl very sweet, you can translate it in tagalog like this: (1) Sa tingin ko, malambing siyang babae. (I think she's a sweet girl) (2) Sa palagay ko, siya (girl) ay malambing. (I think she's sweet) (3) Mukhang malambing siyang babae. (she looks like a sweet girl)