Aged and expensive.

Although Ultimatemember fulfills its basic purpose, it appears aged. Need to define the maximum file size for uploads? While other plugins allow you to define “5 MB”, with UM, you still can only enter it in bytes. Want to link to a Soundcloud-Track? Good luck finding the TrackID, the only means to embed the track. Apropos embedding – Users cannot embed other media in their profile pages. Upsetting is also the pricing strategy. You must pay US$ 299 per year to have access to all plugins, whether you need them or not. The default theme is boring, to say the least, so you’ll be spending hundreds of hours spicing up the theme or paying someone to design one for you because UM is incompatible with most modern themes.

Besides, the main content sidebar is aligned to the left, not the right. If you know about scripting and programming, that is not a problem, but if you don’t, you’re screwed.