I not too sure why others have not reviewed this app, but I guess I will be the first. On the Job (OTJ) is a pretty functional piece of software. The organisation of the task timing is nicely done. You have clients, and under each client, you have projects. Within these projects you have jobs, or tasks.
Each job has a title and notes as well as the times in which you worked on the job. It has a list of all the dates and starting times you activated the timer for that particular job. You can invoice 3 different filters -- Invoice this Job, this Client or All Jobs. Then you set the date range.
The invoices are okay. You can choose from templates and customize them if you want. This is where the app breaks down a little. The customization is a little awkward and hard to get "just right", so if you are a perfectionist, good luck getting exactly what you want out of them. But, overall you can get a nice invoice to send to you client.
Another cool feature is the menu bar icon which you can start and stop timers for any of your jobs. The app has a great inactivity monitor which if inactive for too long it warns you and gives you a choice to stop and remove time or continue. The one thing it misses that I would like is a pause.
Pros: Clean interface, nice organization, inactivity monitor, menu bar control and it hasn't crashed on me yet (I have been using this for months).
Cons: Invoice "designer" is a bit awkward and hard to get "just right"; no pause job, just stop job and I would like, but don't need, a notes section for the different times (nice if you want to leave yourself a note from where you left off).
Summary: A good solid and stable app that does exactly what you need and quite a bit of what you want. It is a crucial piece within my workflow.