Is diamond worth it?
Could you have won the game you just drew? If you think you would take the time to review your games and find improvements, it can be very helpful.
I don't know about diamond. I have platinum and think it's worth it. The other features locked behind diamond I can get for free on other chess websites. But the same could be said about many of what I get with platinum. I think it's really more about what you can afford and what it's worth to you.
I have it and I would say it depends. Lichess has free puzzles. There is kind of a difference between chess.com puzzles and lichess ones, and I like having access to an unlimited amount of both. I prefer analyzing my games without the game review. It's fun to see how many great/best/brilliants you had in a game, but it's better to analyze just using the stockfish engine lines instead of game review.
There are free courses that come with getting premium, and some of them are pretty decent, but I wouldn't recommend most of the ones I've seen to beginners.
But hey, if you really like chess and want to turn it into a serious hobby then I think it's not a bad investment.
If you plan to improve in chess - you will get a lot of options.
Could you have won the game you just drew? If you think you would take the time to review your games and find improvements, it can be very helpful.
25. Nxe7+ was better, as 25. Rxe7 runs into 25. Rxc2+, followed by 26. Rxc3
Probably not since you can get free puzzles and lessons on lichess. Only thing its good for is the game review and it is easily bypassed