My experience with Uplay comes from Assassin's Creed 2, Brotherhood, Revelations, and Heroes 6. And I've never had it be "smooth", although it hasn't been catastrophic, either - mostly a lot of small annoyances most times I have to use it, here is a list:
- it's slow. You start Steam, you start the game, that starts Uplay, it loads for a while, then it gives you a "play this game" button and then you wait for the actual game to load.
- it's mostly useless - as described above, it does exactly the same as Steam (you launch it, you start a game) but it's after you've done it anyway.
- it has achievements...which are shit. You get awards for completing some of the achievements in the form of U coins (I think that's what they were called). And, of course, the achievements you need to complete are the shittiest ones, they are roughly 1. At about 10% progress in the game (a bit after you start - go through the tutorial and start the main quest) 2. at about 50% progress 3. at about 75% progress. 4. when you finish the game. Yeah, they are that lame. Some times one of them may require actual effort (as in, it's not something you just get from playing the game) but not really that much. For each game, I've only ever seen 4 that give you awards.
- the rewards you can buy with the U coins are shit, too. Most of them, at least. Some are OK - slightly more ammo for the pistol in AC2, for example - a small boost in the game but it's good - you go from 6 to 10 bullets (if I remember correctly) which is not game-breaking but welcome. Some give you an extra cosmetic option which is OK, but some are shit like wallpapers. Why the fuck would I want to spend some currency on wallpapers when I can google " wallpaper" and get more and better ones? Overall, some of the rewards are meh but OK, others are meh, others still are not worth it and every once in a while you get something that's good which just raises the question, why didn't they have more like those.
- the achievements don't work sometimes. See, it's all well and good that they give you awards...aside from when they don't. It was AC2, I believe where I didn't get any of the 4 awards at all...and they were all progression based. And yes, I've completed the game.
- Uplay is buggy. Let's see:
-- I've seen it downgrade itself - it got updated with new UI and everything, then few days after it went back for some unknown reason;
-- several times it managed to forget my login, even if I had played the previous day (and I always tick the "Remember login" because I don't want to keep filling them in);
-- for a while it didn't quit properly and I had to kill the process, otherwise it hang around and I couldn't relaunch the game otherwise;
-- amazingly, sometimes it failed to connect to the Internet until it was relaunched (that was relatively rare, though, but frequent enough to not be written off as a complete accident);
-- it managed to somehow obliterate itself once and I had to reinstall it, for bonus points, it didn't even know it was obliterated as the executable and the registry keys were there, just some of the other vital files were gone so it would try to start, then silently fail[footnote]I think it might have tried to update itself and failed miserably. Possibly becuase if it did try to update itself, it would have been in the background without my knowledge, and I might have restarted the PC or something while it was going. It's the most logical explanation I have, as I hadn't done anything with Uplay for a while and then tried to launch it only for it to suddenly not work, without me doing anything to stop it from working in the mean time[/footnote];
-- for a while it was consistently failing to sync stuff to the cloud;
-- I've seen it fuck up the translations and never bothering to correct itself - as in, all labels, names and so on in its UI would be set to the actual translation keys (stuff like "main.button.play" or "popup.button.ok") instead of the proper words (so, "Play" and "OK" respectively). And since the translation key is not even supposed to be there, if it doesn't fit in its container you only get what does fit. And when you get a popup with two buttons but they both say "popup.butto" because the key doesn't fit either and you you have no clue what each is supposed to be, it's annoying. And the content of the popup is another translation key where you can't even guess what it refers to;
- maybe, sort of not exactly Uplay related but I think it fits the banner - even if the games there could be played offline that doesn't mean that you're safe. In Heroes 6, in particular if you play online and your connection drops, even for a moment, you're immediately booted out of the game. Even if you're currently in battle. And no, there is no saving either - you only get your last save, whenever that was.
- the achievement system inside Heroes 6 itself was hanging off Uplay and it was pretty much more of it. More of the useless stuff and the broken stuff.
-- I've completed one particular achievement there maybe, like, half a dozen times because it randomly decides to reset itself. I'm not complaining, as it kept giving me whatever the achievement currency was, but it is still broken.
-- Another achievement was mostly stuck.
-- Few were random and arbitrary for no good reason.
-- The rewards you can get with the achievement points, are terrible, anyway. You can get a bunch of portraits which are completely useless, or you can get the in-game ability to regain movement when you spot an enemy hero. Guess which one makes more sense to be picked up. The cosmetic rewards aren't really...rewarding, the functional are either useless or too good to pass up.
-- And (at least when I played the game), the achievement points you can get are limited (barring exploiting bugs like the bug I had forced on me) so you can't even get everything.
-- Oh, and the damn Legacy artefacts don't gain XP from quick combat, which is either a bug or a really, really annoying feature. I'm dumping it here as I think it deserves a mention.
Overall, it's a lot of annoyances that keep me questioning why Ubisoft think it should exist. Don't get me wrong, it's never been obnoxious or unbearable for me, but as I said, it's a lot of small and constant annoyances. The fact that I hardly ever used it and it still seen enough to write all that text above, still serves to show that Uplay is problematic. And those are not the entirety of the problems I've had. Heck, my problems aren't even the entirety of problems most people have had - I've seen mentions of lots more - some you can find in this thread - obliterated or corrupted saves, problems with games due to Uplay itself, various problems with using it and so on. It all serves to show that it's problematic. And the fact that Uplay isn't really new and has had issues for a while various ones, a lot of them, spanning across years and people, some related to the very thing it's trying to be - an achievement system, a gaming platform, a DD service - it has tried its hand all and it has failed in each at various points in various ways. All of this does suggest it's not a really good service. Whatever the hell it's actually trying to do, as that's another downfall of it - it's wants to to juggle several roles but at best it performs tolerably but nothing worth writing home about, occasionally a mixed bag of something above average and a lot of blandness, and a lot of times it's sub par to various degrees. Again, all of this suggests it's not a really good service.