Opinions on chess.com memberships
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I don't know about v3, but I found the basic membership worthwhile in v2 for Tactics Trainer and Chess Mentor (only 5 lessons a day but that was plenty). I wasn't willing to pay for Platinum. Now that I have it I barely use the extra privileges--I seldom have the opportunity to watch videos and when I do, there are plenty of free ones around.
If you are involved with teams/groups, it's worth noting that many group roles require a paying member, so you can help your team out.
Reviews:
Tactics Trainer works for me. Many people complain that it doesn't allow for multiple solutions (some other sites do). There are often useful comments on each puzzle and those make it more valuable.
Chess Mentor is a mixed bag. I found it *very* helpful for endgames, which were a weakness of mine; completely unhelpful for openings; sometimes good for middlegames but you have to pick your lessons carefully.
Video lessons are also a mixed bag (though I have not done very many). It's an inherently slow, ponderous way to teach compared to print, so the presenter has to really have organized their material.
Being able to run tournaments and be super admin in groups are nice bonuses but not worth the price by themselves.
Chess-mentor is the most valuable thing that you get from Premium, with the videos ofcourse. Tactics are also very nice if you can have some long sessions where you actually learn some new motives. If the tools are used properly - you will improve a lot with what is on chess.com. Atleast it worked for me. 
-- Remember to mix in some gameplay to process what you've learned
Which memberships are worth it on the new V3? I want tactics and I believe certain categories can be chosen on this new version, which is good. How good is Chess Mentor? I wanted to get a membership simply to have chess mentor. How good are the video lessons? I don't know how useful these are since I have never seen any. . .All in all I would like some reviews of the different things that chess.com has to offer for membership players and which ones seem to be worth the cost of membership. Thank you.