I've observed in the past that all churches, even those who don't consider themselves "liturgical," nonetheless do have a liturgy, by which I mean that each church has a set pattern by which that community worships God. A pattern that, if it is disrupted, the disruption is not only noticed, but often resented. I am by no means immune to this observation. I worship with the congregation I do for many reasons, but one of them is that I find myself more or less "in tune" with the patterns of worship there, and when those patterns are disrupted, I don't always like it.
It should hopefully be obvious that I don't mean to say that people should never attempt to worship God in new ways. Indeed, I worry that without worshipers willing to break old patterns as they worship God, our worship will become stagnant and lose some of its meaning for our own lives. I am only here observing that such attempts risk offending some worshipers. This can be unfortunate, but we can't let the fear of such offense stop us before even making the attempt to explore fresh ways of worshiping God more meaningfully.
That said, I definitely do have pet peeves, much as most people do. Some people talk about the "Worship Wars" in which supporters of one style of worship music (say, for example, the praise choruses of the past couple of decades) find themselves fighting against the supporters of another style (say, for example, the traditional hymns as have been found in printed hymnals for the past several hundred years—I should note that there are many other types of worship music, and indeed many subdivisions even within these two groups. I use them here only for the purpose of illustration). That's not quite my issue. My peeves are generally less about the type of music that is used, but more about how that music is used.
For example, I'm a bit of a perfectionist. If the words are made available to a congregation via PowerPoint or similar projection technology, it bugs me when the person responsible for projecting the lyrics waits until a verse has already started before showing those words to those of us in the congregation. Don't assume we know the verses already! We may need to see those first few words in order to be ready to sing along once the worship leaders start up again. Give us a few seconds lead time, rather than forcing us to jump in on the second or third word once we realize what's going on!
In a similar vein, it annoys me when leaders fail to double-check the lyrics they are working from (often on a sheet prepared for instrumentalists) with the lyrics the congregation will see (either in the bulletin or via projection). I imagine most of us can recall a time when the leaders started to sing an entirely different line (or worse, an entirely different verse!) from what the congregation was expecting. This is not only embarrassing for everyone concerned, but it can yank people right out of the worship experience. Always, always, double-check!
Finally, there is a question of what I'm going to call "stage presence." People have different styles of leadership, and while I don't want to get too much into the "worship vs. entertainment" discussion, there is nonetheless a sense in which the appearance of the leaders up front will set the tone for the rest of the congregation's worship. Leaders who recognize this fact sometimes end up coming off as "inauthentic" in their efforts to appear worshipful. The best way I can describe it as being too "earnest" in the way that they, say, close their eyes and raise their hands and modulate their tone of voice while they pray. (Not related to upfront leaders, but this video demonstrates in a humorous way how people can self-consciously adopt various postures of "worship.") It is undeniably wrong of me to assume that I know what's going on in their own hearts as they worship God, and to the extent that they really are simply expressing their natural worship posture, I owe such people an apology. But when it appears inauthentic to me, it bugs me.
This is all just me. Not only don't these same things bother other people, but other people would be no doubt shocked and hurt to learn that I am bothered by them as I am (hence, I have attempted to make my statements as general as possible, not referring to any particular music leader or congregation). Even so, I think the basic ideas are worth keeping in mind. While we shouldn't be too afraid to do things that may bother some who simply can't adapt to change, we should also be willing to listen to those who may have different perspectives than we do. Maybe, just maybe, God is trying to tell us something through their concerns.
A different pet peeve of mine is how many Christians, especially in Evangelical churches, use the word "worship" to refer almost exclusively to musical matters. Although I am primarily interested in music in this post, I have tried to be careful with my language so that, if I use the word "worship" without explicitly referencing a musical context, the concern could apply to aspects of worship that are non-musical, as well.