It's great that it's finally out but of course it needs major fixes. I have found a few upgrades that it can have to make the experience for spectators a little less boring.
-- One aspect I found to bore me was the audio. You don't hear the announcer calling out kills or streaks, it's just a silent game with *thump thump* every other second.
-- The champion lock screen/ info screen is so small, too hard sometimes to tell what they have as items or the numbers on their stats.
-- CAN'T CHAT! As of now it's only in custom games but please allow spectators to talk with one another and share their feedback or what type of bugs they have found with each other. Also it wouldn't hurt to talk with the players in game (it's only custom and it's still in beta wouldn't hurt to give the players feedback as well and well custom games don't really bring in an opposing player team it's always bots).
-- The tab window should be the same size as it is with any game.

i think its horrible. but thats only because of the fact that i've been trying for 20 minutes to spectate just ONE game. i still have yet to even come close. they are all custom games so none of them ever begin anyways. just a bunch of people joining and leaving over and over. the games that do have people joining are always full before you even have the time to click spectate on the list. 2 slots is definitely not enough. any games you actually can get in are all bots or never get started. I thought maybe this would be a good way for me to learn how other people play and pick up some pointers on what to improve for me, which would be fantastic, if i was even able to spectate anyone in the first place. this new wonderful "spectate" feature is literally non-existant so far for me.

I hope the spectator limit is lifted eventually, unless that's just a default? But I haven't seen a game with more than two people allowed.

I agree with the silence. I wouldn't mind if they did new neutral announcements like "A champion has been slain" or something instead of ally/enemy.

My biggest problem with it is that you can only navigate the map using your minimap. Unless that was a bug... But it's really inconvenient to follow a jungle fight when I need to move using the minimap, instead of clicking on the main screen.

Currently there is a 10 person limit to spectator mode - at least there is on the PBE. Unsure about Live. If it is set to 2, probably only for a limited release type of testing environment. See what bugs pop up with it, and etc.

Neutral announcements would be nice - I was able to move the map normally when I used Spectator mode, not sure why you couldn't?

Also to OP - yeah, those are all things we've spoken about in the PBE a while, it'd be nice if we could chat, or perhaps ping for fellow spectators, a few other improvements would be nice - like joining a friends game in progress to spectate.

I think all of that is down the road though - this is just a first iteration.

Hope that helps!

You can still PM players ("/w username message" or "/r message" if they talked to you first).