Like many of Shakespeare's Sonnets, Sonnet 94 is all hot and bothered about problems of death and decay. These ideas first appear in line 6, where we learn how the powerful people are able to counteract the decay of nature, and then really come to the forefront in quatrain 3, where we learn how the lives of the powerful people parallel the life and death of "the summer's flow'r." These themes, and the speaker's generally bummed out attitude toward them, are typically Shakespearean.
Also very Shakespearean is Sonnet 94's use of the sonnet form, not to state the obvious or anything. Like most of the sonnets, Sonnet 94 divides its ideas up into three main sections, following the divisions of the rhyme scheme. The first four lines—quatrain1—talk about powerful people, and how they show one face to the world, while keeping their inner selves hidden. Quatrain 2 talks about the success of the powerful people compared to others, and quatrain 3 compares this whole situation to flowers in a garden. Then, the couplet (the last two lines) sums up all these ideas.
Finally, another feature of Sonnet 94 that has Shakespeare written all over it is its sheer complexity. This poem is full of lots of weird switchbacks in emotion, so you can never quite tell if Shakespeare is praising these powerful people, criticizing them, or a bit of both. Putting it all together is bound to be tricky—which is just what we've come to expect from Shakespeare's fertile mind.