I would like to have option to find people from other organizations/tenants and chat with them.
1/ Teams user to teams user.
2/ Teams user to Skype for Business user.

Treat users in your own organization but on different tenant differently than a regular guest. We should not have to add them a a Guest user in our tenant.

When you've been given access to a team as a guest there is currently no way to be alerted. All the little red notification only appear when you visit the guest team's tenant within Microsoft Teams. A notification on the account in "Your Accounts" would probably work.

Instead of having to switch Tenant, why not add a section Guest where Teams from other Tenants are displayed while still displaying our home tenant Teams.

Have option to allow guests to create tabs in a channel. Guest already have access to add channels, if enabled, but can't add tabs.

Current for guests invited in Teams, we can see a Guest contacts will be created in O365 Admin Portal --> Users --> Guest users. However, there is no detailed information showing who invited the Guest, which Teams group this Guest belongs to and there is no easy way to manage these Guests accordingly.

We would like to have central management feature for Guest users created in Teams.

Allow Guests to Create New Contact Group. Having tested, they cannot do this at present.

Allow to share screen to External Contacts directly through Chat. Currently we can only share our screen to external contacts when in a meeting. We can share screen to our internal colleagues but not to External Users. We will be needing to add them as a Guest Users first.

To be GDPR compliant we would like to hide the guests e-mail adresses by default in Teams.

Let Guest access work like SharePoint guest access.
Currently guest users are required to have a Teams subscription in their own tenant. It would be very helpful if guest access in Teams would function like guest access in SharePoint Online, including restricting the ability to invite guests to only those already in the Azure Active Directory associated with the tenant.

Same concept already in for SharePoint Online sites, disable guest access on tenant level and set for special single sites only "allow external sharing", must be possible also for teams (o365 groups), in same way, current situation at the moment a show stopper for us, current domain handling not a solution

Allow Guest Access users to easily join via Team Code or link to Teams Channel. Adding guests one by one can be tiring when you're inviting hundreds of guests to a Team.

If anonymous users are in the lobby (e.g. joining by first name only), it would be good to have a feature that allows communicating with users waiting in the lobby for identification (e.g. ask them to provide additional informaiton who they are). At present, you only have accept/reject option.

Need ability to set security controls at the Channel Level, especially when External Guests are invited to the Team site.

Currently external sharing can be enabled/disabled for all Teams tenantwide at once.
It will be much more flexible if the external sharing could be enabled on per-team basis.

How do you change the Display name of a guest AFTER the invitation is sent? There must be an easier way than this:

http://lynciverse.blogspot.nl/2017/09/how-to-change-display-name-of-guest-in.html?m=1

While guests can now join a Team meeting, there is no "promote to presenter" option to allow them to share their screen. Without this, I'm forced to fall back to Hangouts or Zoom.

Currently Teams Federation is provided through Guest access. There isn't much published collateral on the list of features (i.e. SIP to SIP or SIp to Other) defining what is required to build Federation with Partners especially where partners are on Skype and enterprise customer could be fully on Teams. Documentation is needing to provide customers guidance on how would you go about configuring with an OnPrem solution or what is needed to support federation in general. Full Federation guidance documentation is needed for these scenarios.