At a Glance
The interface is somewhat complex and a bit non-standard, with a multi-tab display showing your active auctions, statistics, and a to-do list on the bottom, a calendar on the right, and general information on the left, with a small search bar and menu on the top. The calendar drives of the program; if an auction you're paying attention to is due to end on a given date, that date is marked. Click that date, and you see the expiring auctions. As a side benefit, you can use the program as a basic calendar/scheduler, adding in meeting times, general notes, and birthday reminders in addition to keeping an eye on auctions.
Overall, I personally found BuyerTools a bit less friendly and intuitive than others in the same niche, such as Prospector Lite and Auction Sentry. Searching, for example, produces a hard-to-read drop-down menu of results, instead of a more typical grid-style display. If you wish to change search order, you need to do so in 'Preferences', instead of dynamically switching it from, say, price to end date. I also experienced a one-time problem with a window not closing after it was done communicating with eBay.
On the other hand, BuyerTools is completely free; the 'Pro' version offers multiple eBay identities and phone support, but is otherwise feature-identical with the free version--a nice bargain. My issues with the interface may simply be due to expectations; those without assumptions about how these programs "should" work may find BuyerTools Reminder quite easy to use. The ability to get a working, if somewhat bare-bones, personal scheduling tool in addition to the main utility is a nice touch.