I was just looking over the last 10 champions being released and it doesn't seem to contain many viable ones, especially when compared to champions released prior to that. Note that these are simply my opinions based on my own observations and I'm looking for feedback from the community.

Viktor: extremely buggy when released, still quite buggy
Sejuani: instantly went on the floor as a bad champion
Ziggs: I still see him occasionally, but much less since his nerfs
Nautilus: makes a great tank late-game, but if the nerfs to his already weak early game go through this could change
Fiora: occasionally seen, though overshadowed by so many other picks
Lulu: really popular on release, but I infrequently see her since her nerfs
Heracim: quickly was found lacking, I haven't seen one in ages
Varus: extremely popular on release, but then people realized he couldn't compete with other picks
Darius: strong out of the gate and still used frequently
Draven: not a bad champion, but can't seem to compete with other picks

So basically from what I can see out of the last 10 we've got 2 champions that are still good atm, 2 that were competitive but aren't seen very often since their nerfs, 3 that are ok but aren't competitive picks, and 3 that were just complete blunders from release. I'd like to hear other players' opinions on the matter.

Here are the 10 champions prior to these for use as a point of comparison:

Wukong: still a good pick
Skarner: sucked on release, but they fixed him up, then made him once again extremely mana dependent
Talon: I've never seen one that didn't suck
Riven: still a good pick
Xerath: was a good pick for skilled players, but then they adjusted his ult making it stupid easy to dodge
Graves: currently a top pick
Shyvana: still a great pick
Fizz: still a good pick
Volibear: quite strong on release, still viable but rarely seen since the nerfs
Ahri: currently a top pick

This puts it at 6 competitive picks, 2 viable picks, and 2 broken.

If you've never seen a Talon that didn't suck, then you've never seen Talon played right (or, possibly, never seen a Talon picked right).

i think that some of the champions listed are viable in competitive and have their advantages, but the competitive teams aren't as sure that they'll be as viable as say, graves or morgana, because they haven't been played as much. for example, the popular opinion on nautilus was that he was "good" before he was used in tournaments.

Keep in mind that, sometimes champions take a while for the league community to understand and get good with. From this logic it may be the norm that newer champs aren't seen as quite as competitive as older ones. I remember when anti first game out her orb missed so much. Even today if I play in pub games, the mid ahris I face are jokes, but that doesn't mean she is a bad champ or can't be lethal in the right hands. Maybe there is a correlation but it's not a strong one. I main viktor right now and even though his laser is buggy he doesn't ever fail to be competitive if I'm controlling him.

Viktor: True.
Sejuani: Semi-true. Can still be used competitively, just the niche for what she does isn't there.
Ziggs: He's balanced so he's not in every game for sure, but still a good bursty champion.
Nautilus: His nerfs aren't so bad as to break him by any means. He is still a CC engine, even if they add the ~4 sec on his Dredge.
Fiora: She is with Master Yi in the "no good place to put her in the META" role
Lulu: Seen occasionally in high ELO play. Would say she is definitely still viable.
Heracim: TheOddOne plays him occasionally (but not in tourneys that I've seen) but yes, he has his problems.
Varus: He is still viable, just not top-picked.
Darius: True
Draven: Is viable.

I think your definition of "still good" means "top picked all the time." Most of these are viable choices (aside from Viktor being the clear odd one out) though not 100% first-picks. The champion pool for competitive play is very narrow due mostly to the current META, which does not reduce so much the "competitiveness" of the champion but rather they are not utilized based on what everyone is going for right now.

I see what you guys are saying about a champion's viability and how much use they've seen so far, also they get adjusted over time. I still maintain though that the last 10 champs have (in general) been crappy compared to older champions.

edit: deleted my last statement.

Viktor, is a solid pick, though his bugs still need to be dealth with. Ziggs is a solid pick. Nautilus is a solid pick. Lulu is a solid pick. Varus is a solid pick. Draven is a solid pick. 6/10 isn't bad and is, if anything, about their general average.

I do find it amusing that you somehow argue that champs that ended up needing to be nerfed after release somehow indicates that is riot releasing champs that aren't viable for competitive play.

The future of LoL is not in jeopardy in any way. Their current design focus is to bring new/spice up interesting gameplay elements:

Viktor: Laser and controllable ult
Sejuani: Long-range skill-shot splash stun
Ziggs: Long-range AOE bomb with warning, bouncing skill-shot
Nautilus: Hook that hits terrain, homing knock-up.
Fiora: Ricochet ability, untargetable ult
Lulu: Polymorph, Enlarge person
Heracim: Charge knock-back and Ult-fear-charge that goes through walls
Varus: This guy is more traditional.
Darius: Executioner ability, AOE pull, spin with AOE dependence
Draven: Juggling, pseudo-global ult with boomeranging

Some of these might fall under merely being "quirky" but it is what makes LoL interesting for a wider variety of people. Some of these ideas end up making it to high-level competitive play (Nautilus, Darius, ~Lulu, ~Draven), some don't pan out (Viktor, Sejuani) and others are enjoyed but aren't considered "optimal" enough for the highest-ELO/tournament scene but find a home with others.

The other reason Riot is making the changes they are, from what I can tell, is precisely BECAUSE of the power-creep of the previous batch of champions. Ahri, Shyvanna, Graves and Riven (with guest appearance by Skarner at times) were, upon release, some of the most powerful champions. They got their nerfs/changes to have them fit in now, but it could just have easily have led down a different path.

If you've played any Magic the Gathering, or many MMORPGs, anything with expansions etc is that many developers will resort to "power-creep" to keep a game fresh. MTG for instance keeps theirs in line by having different "blocks" and by fluctuating overall power level per set. Riot has been working to readjust their priorities away from overall power and more towards creating new experiences with each new champion.

I think Riot is doing a good job that is merely my opinion.

Nautilus is extemely competitive the nerfs are just going to bring him into line.