The biggest problem I saw was initiative handling.
The second biggest was that combat was very whiffy; that is, most attacks had no effect. The group I was sitting in on had been playing the system for about a year, and was slowed to a crawl in combat due to those factors; any given combat turn was slowed by the initiative, the individual attacks weren't terribly effective - they weren't able to get wounds reliably except by ganging up. Nor were the opponents. It was a slog. This may have been due to unusually high armor, or not, but it was slow going. The players were using cover, as well, as were the opponents.
Lots of ineffectual turns is no better than slow, cumbersome, but usually effective turns.