This is something that has been a real bother to me ever since the levels of monster were changed from the Big Bang update and with new monsters added in so I will list all the problems I have in a numbered list then explain.
1) The sets are inconsistently leveled. Perion has monsters that go from 10-15, 20-25, 55-58 and 60-65. With such inconsistent levels in makes it rather annoying to complete a set of cards if you have to keep coming back for some of them.
2) Some set can't be completed anymore. Mushroom Kingdom set still exist in the Monster Book as does Kerning Square both of the sets are unavailable anymore. Now this doesn't affect anyone who has already completed it but for those that only had some of the cards or are making new characters it's a set that can't be completed. It just makes it pointless to keep in the game if in can't be completed by newer characters.
3) No new set for newer areas. The set don't seem to include anything past the Henesys Ruins area. Many new areas and monster have been added since then but are receiving no cards or a set for them to be apart of. It makes the entire set idea to seem pointless if it isn't going to be updated with the rest of the game.
4) Party bosses are apart of a set. This only bothers me a bit because almost no one does some of these party quest anymore and it makes it hard to complete a set. King Slime is apart of the Kerning City set yet is a party quest only enemy. I would also like to point out party quests are no longer in their former locations and as such don't have the some connection they use to not to mention that for most of them you need to be level 70 to do them, which is far above the levels of the monsters in some of the sets. I suggest either removing these cards or just make a brand new set for party quest bosses.
5) The stat bonuses are completely stupid. I can understand that the Victoria Island Friends set is easy to get but who in their right mind thought that 5 HP would be a worth while bonus. 50 HP i can understand but 5! this is so stupid as the bonus provides practically nothing for completing the set. Many other set do this too and some of them are much hard to achieve with such little worthwhile results in the end. What was the point to the sets if they are more of a joke for completing most of them as the stats they give are pointless.
This is all I have to say about the monster book sets. I really love this set idea and I loved going about completing them when they were first introduced (even though the maplestory mesos were still just as pathetic as they are now though you did get a nice EXP bonus for completing them). These set need to be updated and need to give appropriate stat bonuses if they want to maintain a purpose in this game or players will just see it as a waste of time if they get no real benefit from doing it.