While I feel schooling and training are important, what is preached is more important. A man could attend the finest seminaries but still preach awry.
I have seen several untaught men accurately divide the word of God, and I have seen many learned men do the same. The bottom line is that a man preach what the scriptures say, and that he does so in a manner that can be understood. No one can be edified if what is brought forth makes no sense.
One problem I have seen among those who have not attended seminary is that they tend to get distracted in preaching. Many ride their own little hobbyhorse, veering off on their pet peeves a lot of the time. And many have no idea of how to lay out a sermon so that it has a beginning, a middle and an end, much less make parts of it applicable to day-to-day life (points in a sermon)... most just "rear back and ler 'er go" without much preperation (study, yes; preperation, no).
Take it to God. Make it a priority in your prayer life, and let Him lead.