Here's a piece complaining about inferior horn playing (French horn, that is) in New York orchestras this year. The French horn played well is one of the most sublime instruments in the orchestra, able to go from beautifully lyrical (think Brahms 1st) to harsh and biting as the music demands. But it's devilishly difficult to play and to keep in tune, and those are the modern versions. The old Baroque period instruments are notoriously unreliable, prone to crack and slither around the proper intonation of a note.
When a played in a community band a few years ago, one of our hornists had decided to try to move beyond the amateur status we all had (at least at that point; some had played professionally at various times, including in the Metroplitan Opera orchestra) and work at his instrument enough to go professional. I lost track of him so I don't know how it turned out, but it struck me that he figured he would have to practice at least four hours a day to get good enough -- and he was already not bad at all.
Apparently at the Mostly Mozart festival this year, the horns in some of the period instrument bands had trouble, and music critic Allan Kozinn felt obliged to call them on it, suggesting that when people in an audience pay money for a ticket they expect to hear good playing, not excuses. In the process he teaches a bit about just how difficult the instrument is, which he fully appreciates. LIsten to the Mozart horn concerti some time if you want to hear the instrument used skillfully.