First and foremost I'd like to say, that aside from the bugs and downtime (to be expected), I'm generally enjoying the game quite a bit so far.
Now, I'm a summoner at heart, and I'm certain that this has been voiced on these forums before, but I'd just like to add to it: summoners don't feel like summoners. There simply aren't enough options. Now, I think that can sort of be said for all classes, as honestly, the amount of abilities right now is kind of lacking, but with summons....you have a maximum of 4 from what I can tell (two from Daedric Summoning, Daedric Summoning Ultimate, and the Undaunted spider synergy)
As an Elder Scrolls game, that's pretty sad. Where are the options? Where are the Daedra? The Atronochs? The undead? I mean, I love how summoning works, it's cool, and I get it if you don't want summoners running around with packs of monsters at their disposal....but giving us the option to switch in and out is basically what being a summoner is all about. Even if you could never summon more than 2 or 3 at a time that would be fine if we actually had the option to summon in what we wanted to. I know that it's still very early in the game and there is plenty room for improvement, I just hope that I'm not the only summoner who desperately wants their options to be opened up to them so that way we can actually feel like a summoner.