We've had ours for well over five years, and it's still going strong.
The video quality is excellent (clear colour display, b&w in the dark), the working distance is impressive too (works out in the garden, kids' room is on the opposite side of the house).
The talk-back function is great.
The sound sensitivity (not a movement sensor, but a sound sensor instead - works a treat) is adjustable, so can be changed as the kids get older.
Can easily work with two cams - so excellent for a growing family, or if you'd like to have a view of their bedroom and play area.
The button names have rubbed off the ones that are used most frequently, but the controls are very intuitive and after a short while you don't need the labeling anymore.
Love it! Wouldn't go back to an audio-only monitor now - having a video is so much better! Save yourself the upgrade costs and just go straight for a video monitor.