Many of the slots coming out now are just as good as any land based slots.
Maybe it's because I live in an area with no competition, but I would have to say that the online slots FAR exceed the quality of the land-based ones. Not only in terms of graphics, but more importantly, payout.
With land-based casinos you don't get to choose whose games you play (unless you live in Vegas/Atlantic City/Tunica), so whatever your casino offers, that's all you get. Too bad if it sucks.
One of the things that really irritates me with land-based casinos is, you finally get the bonus round and... holy cow! You just won five times your bet! I would estimate the house edge on the slots at my local casino are upwards of 13% - where is the fun in that?
The other edge that online casinos have over land-based ones is that you don't need to bet the farm just to play. You can play 50-hand video poker at $2.50 a whack. At my land casino the best they offer is 10-hand at $12.50 a pop. With online slots you can hit "Bet Max" and only spend 45 cents. The first time I went to the land casino, I popped a $20 into the slot and hit Bet Max, only to find out that I now had $2 left!
And online, there is zero intimidation when it comes to table games. I admit it, I've never played a table game at a land casino. They're always full and/or the minimum bet is too steep for my kind of budget, nor do I have any idea of what the etiquette is, how much to tip, etc. And from what I understand, you will get some funny looks and/or walked out if you don't bet roughly the same amount on every single hand of blackjack... what's the point in that? I prefer to hit and run, not sit there for 6 hours just to break even.
So... the online casinos offer three things that aren't available in the majority of the physical world: competition, choice, and comfort.
If the industry could get regulated here in the US, some sort of networked instant payment system could be implemented where the tax man always gets his (un)fair share and the player can log off, walk down the street to the ATM and withdraw their already-taxed winnings, that would be a very happy day indeed.
While we're at it, any chance they could change the tax laws to be a little more consumer-friendly too?
There are, of course, things that the land casinos have over the online ones, such as much better comps (thanks to the higher house edges) and all the extras - food, shopping, valet parking, etc. But I really don't see online casinos overtaking land-based ones in the future. I see land-based ones moving online, and all games improving (in terms of payout) all around the country due to the increased competition.