I really like the achievements, it's great to collect something and get points for that.
This said, there are two things that really should be improved:
1. Winning a high rank achievement automatically should reward all lower rank achievements automatically.
A example which is totally wrong obviously: Nr. 1 in Nine Men's Morris, a real good player indeed, Nr. 1 since before achievements started, only has the achievements for 1st, which gave him 15k XP. Me, starting out after he reached 1st, and climbing through all ranks with achievements in place already, got Top20, Top10, Top5, Top3, Top2 (him not reachable obviously), for a total of 34'750 XP (actually, T2 was 15k for me already).
2. Rewarded XP for collected XP should be corrected (increased) if the condition for the achievement is fulfilled again and when the achievement is worth more XP meanwhile.
A obviously wrong example here too: I started out rather quick in Connect 4 pretty much as soon as it was released to beta. I was first within a few days, and actually missed some of the lower Top-Rank-Achievements, because the required score wasn't above 300 at the point where I reached these ranks. I slowed down for some days, lost some, dropped heavily, and then picked it all up again. Two days ago, I reached 1st again. So, alltough I have all Top-Rank-Achievements now, and actually fulfilled all requirements just yesterday again, the rewarded XP still has the value of the achievements 2 days after the release of the game. That's 13.3k XP for all Top1-Top20 achievements. Yesterday/today, a player that only started playing C4 this week, climbed through all ranks till 1st, and got all the current XP values. Which, for him, is worth 65.5k XP! So he got 5 times more XP, because he got all rank-achievements just today, while I, meeting all goals yesterday too, already had collected them after the game release, and since am stuck on the cheap value versions...
I hope that you see that this is really wrong, and needs to be fixed. Thanks!