They felt sluggish and slower loading.
Which versions of which were being tried ? On opensourcecms when we try both , GL is distinctly slower. However comparatively speed is same on both. On my machine under localhost both are a snap .
It all depents on the audience you are trying to reach and the features you need.
Since e107 is more easily customizable and more features can be just turned ON or OFF at will at a single click I guess with e107 I can reach any audience - with GL my choice of audience becomes limited.
Regarding messy results :
GL does not work properly with both reg glob on and off
GL calendar is a mess - users cannot delete personal events
For sending simple PMs one has to pay for the module. I guess PM is used more than search. Personally though I find e107 search quite OK.
As well as the fact news submission is more handy and dynamic - users can submit images or have the facility of htmlarea turned on or off as well as plenty of language packs.With GL any user wanting to submit image has a supermessy procedure - submit news, then email the admin the images separately.
Installations of forum and gallery like 4images is supermessy - one has to mess with so may files in GL - its disappointing. None of the cms-es e107, drupal, mambo has such a difficult installation.
Structurally both are php-nukish, that way Drupal is way ahead with its "node" system and much more stable appearance and solid performances.