…is a big drawback

The downside can be…

…can be a stumbling block

…is a catch

One of the flaws of this kind of approach is…

One of the faults with this thinking is…

A problem I see is…

One of the obstacles is…

Some of the difficulties are…

…can cause difficulties

…is often a nuisance

Complications such as…come into play.

One of the weaknesses is…

The losses could be…

…is a liability

…is an ill effect of…