I picked this up when my mountain bike bottom bracket seized. I figured removing the old bottom bracket wasn't a big deal with vice grips but probably not a great idea for installing the new one. The right tool is always helpful when doing a job and this isn't any exception.
This bottom bracket tool is a must have if you want to change your bottom bracket, clean hard to reach places, etc. It works great and how you'd expect it to. Grease, oil, and dirt comes right off if your bottom bracket tool (if dirt can come off of my bottom bracket tool because of a dirty bike, they it is certain that it was clean right off of yours).
I do all my own bike maintenance on our 4 bikes, 2 road bikes and 2 mountain bikes.
Having the right tool for the job is critical to completing the job without frustration or damaging the bike or yourself. Although I've not yet got around to using this tool all the tools I have purchased from Park are great tools and I would highly recommend Park Tools.