  We employ the $B\to\pi$ form factors obtained from QCD light-cone sum rules
and calculate the $B\to \pi \ell \nu_l$ width ($\ell=e,\mu$) in units of
$1/|V_{ub}|^2$, integrated over the region of accessible momentum transfers,
$0\leq q^2\leq 12.0 ~GeV^2$. Using the most recent BABAR-collaboration
measurements we extract $|V_{ub}|=(3.50^{+0.38}_{-0.33}\big|_{th.}\pm 0.11
\big|_{exp.})\times 10^{-3}$. The sum rule results for the form factors, taken
as an input for a $z$-series parameterization, yield the $q^2$-shape in the
whole semileptonic region of $B\to \pi\ell\nu_\ell$. We also present the
charged lepton energy spectrum in this decay. Furthermore, the current
situation with $B\to \tau\nu_\tau$ is discussed from the QCD point of view. We
suggest to use the ratio of the $B\to \pi \tau\nu_\tau$ and $B\to \pi\ell \nu_l
~(\ell =\mu,e) $ widths as an additional test of Standard Model. The
sensitivity of this observable to new physics is illustrated by including a
charged Higgs-boson contribution in the semileptonic decay amplitude.
