There are some dreadful obscurities this week. Take 29d, I'll spare you the clue but the answer is 'rutherfordium' (I had to cheat to get it). This was an important clue because it was on the left edge of the grid and gave the first letter to seven across answers, but how many people have ever heard of it?
This issue started with the first across clue. To solve it you needed to know the meaning of the Scottish dialect word 'unco'.
Another answer was 'monotreme'.
For another answer I had to search online the names of Roman poets.
I don't mind complex clues, preferably involving witty word play, but when you have complex clues and the answer is a word you have never heard of, then what might have been a fun solve becomes a boring series of Google searches.