Honestly I love the runes and masteries. Right after joining when I leveled to 2 and was told I unlocked a rune slot and mastery point, I went to check it out and read through masteries and tried to find what I liked best.
I wish they'd get rid of t1 and t2 runes, those are just a waste of ip and it's unfair to people who don't know, but otherwise I like the system.
I have multiple mastery pages for the same champion in some cases. You can customize them during the Draft to counter your Lane opponent or go with or against a team comp. They feel like good rewards for leveling up. They also create meaningful goals while leveling rather than it just being "get to 30".
I don't know if I'd have stuck around if not for them tbh. I like this game a lot and hence probably would have, but having the goal of getting to 20 for t3 runes was a lot easier to accomplish than getting to 30 for ranked, which meant I was able to be excited about something in the game I otherwise wouldn't have been able to be excited about. Unlocking a new row of masteries had the same effect.
In general I like it and think it works. My only problems as a new player are IP costs. For the most part all of the best champions are 6300ip. I get it, no one would want a new champion if it wasn't stronger than the old ones, but with so many champions now and the cheapest ones mostly being outclassed, it feels like you need to put in so much work just to get something you can compete with. The free rotation helped, but some weeks nothing good would be available and those times were frustrating. Add in the 20k + ip that was needed for runes, the fact that rune pages are like 7000 almost which means I'm giving up a good champion to get an extra page (so I still only have 2), etc... I think champions just need to be discounted faster. New players have fun trying new champions, and they simply can't afford them. I've played since April, am level 29, and still only have a little over 20 champions, most of which are 450ip and next most 1350.I have two 6300s and two 4800s and 0 3150s I think (excluding free tristana, garen, and alistar from social media). New champions can and should be costly, but they need to be discounted faster so new players don't look and think they'll never have enough to buy all the champs they'd like to try, let alone all of the champs in the game.