No they're really nice, depends on weather conditions of course. The one's over by Santa Pod are more challenging and tend to be quite rutted, but if the weather is bad the Council tend to TRO them until they dry out.
Forty Foot lane behind the Drag Strip has been closed for 2 years now, some cock and bull story from the council about it being dangerous for horses to exit onto the A6, well I've never ever seen a horse done those lanes.
Keep an eye on the Herts Lanes thread towards the end of April and come tag along.