% Dans le préambule
% -----------------
\usepackage{ifthen}
% -----------------

\newlength{\lenpoint}

\newcommand{\point}[1]{
  \setlength{\lenpoint}{#1pt}
  \ifthenelse
    {\lengthtest{\lenpoint > 1pt}}
    {#1 points}{#1 point}
}
\point{1}, \point{2}, \point{1.5}, \point{0.5}