I don't like the LP system. It gives me almost no motivation to win once I reach a certain rank.
For example, I only wanted to hit Gold V so that way I would receive that bonuses at the end of the season. However, upon hitting Gold V, since I can't drop anymore I just literally gave no fucks. If my team pissed me off, GG. I couldn't care less if my team wanted to win. Since MMR is hidden and you don't see any instant drops or anything either, there's no serious repercussions to doing so. Whenever you played using ELO, you would immediately see yourself losing 15 points so you would at least be deterred to throw. Using the LP system, all it does is lower your MMR and you don't see anything happen so who really cares as long as you've hit your target bracket already.
Of course, now if you want to advance yourself, you kind of already screwed yourself over -_-