[chambo622]

Feels old, clunky, and not fun to use compared to Slack. The hosted solution has also had major reliability problems over the past 6-12 months (may not apply if you use the on-prem offering). The mobile apps are very outdated and tend to botch notifications and message delivery/syncing.

On the bright side, the desktop client uses very little RAM compared to Slack.

[shrewduser]

i don't understand how slack is as heavy as it is.

[rrdharan]

It's an Electron app, so it's basically running an entire second copy of Chrom{e|ium}.

UPDATE: Err, or first copy, if you don't use Chrome as your primary browser.