The biggest problem with DirectShow is that available configuration
capabilities can change if you so much as look at it the wrong way.
Previously, configuring devices often didn't configure the device
settings correctly, you would choose one setting and then another
setting wouldn't be compatible with that settings.
Let's take the terrible microsoft lifecam series for example. First,
you'd be at 640x480 happily webcam'ing away, which is using the YUY2
format. Then you decide "hey, this webcam resolution is a bit low. I
would love to have it a bit high resolution so it's a bit more crisp and
clear." You'd select 1280x720, and then suddenly the only format
supported is MJPEG output. However, the interface has to update that
fact, it can't list YUY2 if MJPEG is the only one available for this
resolution. This doesn't just apply to formats either, this applies to
framerates and such as well. Some framerates will only be supported by
certain resolutions which can in turn only be supported by certain
formats.
This causes user interface for configuration to be really be a nightmare
to manage if you want these features to be available to the user. It's
extremely annoying because you have to update all the configuration UI
after something has changed, double check the configuration values, and
if the values aren't supported, update those configuration values.