1. Too expensive
That can vary. If you're buying trades every month for $4 or $5, I feel your pain. But a lot of places have them cheaper. Humble bundle frequently has cheap comics, as do other online retailers. We're talking a couple bucks or less per comic.
2. Inferior artwork (used to be better)
Somewhat agree. Again, it varies. Some old stuff is fantastic, some old stuff is horrid, some new stuff is fantastic, some new stuff is horrid.
All in all, I'd argue that it has gotten somewhat better, though there are modern conventions that bug me - like anime conventions creeping in and a tendency to draw characters with extremely low detail.
Though I'd prefer that compared to my old 90s Liefeld comics any day.
3. Inferior storytelling (too much recap of what has gone before)
Generally agreed. There have been some interesting new storylines (particularly from non-DC/Marvel comics companies), but there's an awful lot of crap, too. I think part of the problem is basically everything's been done before. Marvel in particular has a very pronounced "simpsons did it" streak. But every now and then, there's something exciting.
For example, I really liked the Guardians of the Galaxy comics (the 2008-2009 ones). It's been done before, not even the name is original. But for a while, they really pulled it off.
4. Serial format (it takes too long to tell a short story)
I love the serial format. That's part of the reason I prefer comics/books/tv shows to movies. There's more time to get the audience attached to a character and his/her conflict. Though I do dislike getting drip-fed a story in 20-30 page chunks, so I'll often wait until there's a backlog then plow through them in short order.