I'll round up from a 4.5.
Good: Jenna Ortega plays a wonderful Wednesday Addams. She really delivers that dry humor. The story was solid. It definitely had enough clues to figure out the mystery but sprinkled just enough diversions to keep me guessing/switching theories. The music was great.
Bad: The CGI wasn't great but didn't ruin the experience. There were a few eye roll moments and character jumps that could have been written better. They could have done a better job casting Gomez and Fester, they were both off putting but played small enough roles that didn't distract too much.
Verdict: I had low expectations, but was thoroughly surprised. I would watch a second season.