I've been playing Xcom: EU recently and while I do enjoy it somewhat I do find it to be more frustrating than I would like a game to be and most of this frustration I have stems from the fact that you aren't given a whole lot of information during tactical battles. Other turn based tactical games I've played such as Fire Emblem, Blood Bowl and Frozen Synapse all give the player all the information that they'll need to plan out their moves and then act accordingly.
Probably the most important and frustrating parts where Xcom: EU decides to not give you info is range/line of sight. There is literally only one indicator in Xcom: EU of whether or not there is an enemy in one of your soldiers LoS and that is the little icon in the bottom left of the screen of an alien's head. The fact that you're only given a little yes/no icon to tell you if one of your soldiers has LoS is almost insulting and makes the decision of where to position your troops so they can fire at the enemy a complete and total guessing game which is extremely bad design when you're trying to pass a game off as strategic and tactical. It should also be possible to see your enemies' fields of view so that a player can determine whether sending a unit on a certain course is a good idea or not. In Frozen Synapse you're given a clear and exact area of what your units' LoS is so that you can position them where you feel is best. In Fire Emblem when you select a unit you're shown clearly with red tiles where your unit's max range of attack is and when you select where you want your unit to go you're shown the exact tiles that that that they can attack when they get there.
Another part where I find the new Xcom stingy in giving us information is stats. The only stats for our units that we're shown in Xcom are health, will, offence and defence. While I don't dislike having a minimal amount of stats in a game I sometimes get the feeling that there are more stats in Xcom: EU than we're shown and I really dislike not being told what a stat does or how it works. For example, the game tells us that the will stat helps prevent a soldier from panicking but it never tells us how it helps and it appears to work at complete random. I've had soldiers brought down to one health and they've never panicked and I've had other soldiers take something like 2 damage and panic completely. I've had soldiers seen a comrade be mind controlled and not panic but then in another battle panic when they see another comrade mind controlled. Then there's the defense stat. In just about every other game I've played that has a defense stat defense is used to help reduce damage taken when a unit or character is hit. Not so in Xcom. In Xcom defense is used to help units avoid being shot, not only does defense do something different in Xcom than in most other games but I never saw this info in the game anywhere and had to look it up on the Wiki which is completely and totally unacceptable. The offense stat is even worse because there isn't anywhere in the game that tells you what it does or how it works and because defense in Xcom is different than defense in most other games you can't count on offense being what you might think it is, is it the unit's chance to hit an enemy or is some factor in the amount of damage your unit will do such as a percentage of a weapon's max damage or is it something else entirely. The aim stat in Xcom is also a problem in that it is referenced several times in the game on certain pieces of equipment but a unit's aim stat isn't as readily available to see as their health, will, offense and defense stats are. You have to get into a fight and then aim at an enemy and then press F1 to see you're aim stat. A stat as important as aim shouldn't be available only through such an obtuse way of finding it.
In Fire Emblem you can readily find every stat that has an effect on a unit extremely easily and in the newest Fire Emblem you're even told the calculations for how some stats and skills work such as needing 5 more speed than your opponent to be able to hit them twice. Also in Fire Emblem when you decide to attack and enemy unit you're given a table before you commit to the battle that shows you the health, damage, amount of hits, chance to hit and chance to crit of both units so that you can decide if you want to commit to the attack or to see if there are better options. Fire Emblem also gives you complete access to see your enemies' stats too if you wish to see them. Blood Bowl does something similar to Fire Emblem in that it gives you access to every stat of both your and your opponent's units. And while the effects of some of these stats might not be clear at first there is a dice log that shows you literally every dice roll in the game and the outcome so you can easily learn what you might not know.
A third major part where I find Xcom doesn't give you as much information as you should have is movement of both your units and your enemy's. In Xcom you are shown all the places your unit can travel to and all the places they can dash to and you are shown the path they will take I feel that even that isn't enough. First of all it doesn't seem very clear what a unit's movement allowance is and while a clear and distinct number might not be that important to the end goal it does help in keeping the game transparent to the player. Secondly is being shown what path your unit is taking when you decide where you want them to go. The little glowy line that you are shown should appear instantly and follow your mouse when you move it over tiles rather than only appearing after a second of holding your cursor over a tile. Players should also have the ability to pick a different course for their unit to the same position. If there happens to be a poison cloud between your unit and a good position then you should be allowed to change your unit's course to go around the poison cloud while ending at the same position if it is within their movement allowance. Thirdly is being able to see the movement allowance of your opposing units. Both Fire Emblem and Blood Bowl allow you to see not just the numerical value of your opposing units' movement allowance but also where they can go and if the terrain might affect their movement range. Frozen Synapse goes even further than that but allowing you to take control of your enemy units and make plans with them to try and anticipate your opponents actions before you commit to your own.
While there are plenty of things I do like about Xcom: EU there are also very many things I don't and that I think are objectively bad game design and seeing as Brad and John have cited both the old and new Xcom games as inspiration for Massive Chalice I hope that if they decide to take some things from the games they try their best to take the good parts without taking the bad parts.