I agree with you, I found sieges with fixed amounts of troops boring although it was a good test of your abilities. Stronghold Legends was the last game I played out of the Stronghold collection and I liked it best because it had stream-lined warfare with very few bugs.
First thing I have to say about Stronghold 2 is "Too Many Penalties": This is a bit of a broad statement, so let me explain what I mean. The most important thing to keep in mind when designing a game is that it should be fun and engaging for the player. Sure, you can go ahead and make that indie game with the deep existentialist plot that investigates man's place in the universe... but if it's not fun to play, no one is going to care about it. In general, it's not a good idea to penalize players too much. When players are confronted by decisions, it's better to let them pick between different good options, rather than forcing them to choose the lesser of two evils. You could have the player pick between a sword (more damage) or a shield (more protection) but not let them have both. The key thing is to have meaningful, balanced decisions where the player chooses between several different "good" alternatives. Getting back to Stronghold terms, you can have Vlad and an army of bloodthirsty Demonic Bats, or you can have Aurthur and the knights of the round table. Both are good options, and if a game is sufficiently entertaining, players will want to return to it again and again to experience different, alternative paths to victory.
Penalties in a castle building game are generally something to be avoided. You want to reward players for doing well, not punish them for failing. Worst of all are penalties that accrue to players randomly, for things that they had no control over. There will be some players who enjoy that sort of thing, but most people won't find it to be very amusing. These sort of things should be avoided when designing a game. (Note that penalties are different from challenges; there's nothing wrong with having a challenging game design. The Ninja Gaiden games are extremely challenging, but they are generally not punitive in their design. You just have to be really, really good to win.)
Stronghold 2's design suffers from way too many of these penalties, in which the player is actually hurt for doing something good. The classic example of this is crime, something new to SH2 with no previous precedent in the series. In past games, there was never a peasant who went bad and started stealing from you. SH2's decision to penalize players for ranking up is simply baffling, especially since ranks are still mandatory to build better troops and defensive structures. The game might as well be laughing at you: "Haha, you need this promotion to better defend your castle, but it's gonna cost you!" So in the end the player is literally getting slammed for good play!
It's not just the crime that is the issue, however. There are penalties all throughout SH2's design which help make the game not very fun to play. Gong spwans randomly around your castle along with rats creating huge clouds of plague killing troops and peasnts. Many of the buildings in SH2 are actually not needed or possible to build due to stringent labor limits. One of the secrets of high-level play in SH2 is that you do better by *NOT* constructing most of the buildings in the game, which is surely a failure of design.
Sorry if that was a bit long winded but I think I made my point.
