Personally, I don't believe that Glock's Gen4 G-19 problems have been either understated, blown out of proportion, or have now completely disappeared. In my opinion (and, 'like all things Glock') some Gen4 G-19's are going to run better than others.
I just spent this afternoon kibitzing with two of the best Glock gunmen I've met in quite awhile. While we talked, one of them did me a big favor and performed a beautiful frame stippling job on both of my G-21's. (Maybe I'll post pictures!)
Anyway, the opinion in the room was unanimous: Each of us thought that our 3rd generation G-19's were one of the best carry pistols out there. The fellow who stippled my G-21 frames told a story about how he got sick and tired of his brand new Gen4 G-19 wacking him in the head with spent cartridge cases.
He said he owned that Gen4 G-19 for less than a month; Glock tech support did nothing but jerk him around; and he finally got fed up and decided to get rid of it. So he took his brand new Gen4 G-19 to a local dealer and traded it in on a brand new 3rd generation pistol.
You should see the 3rd generation G-19 he purchased, too! It has a beautifully machined TSD Combat Systems slide that is fitted with perfectly co:witnessed Ameri-Glo night sights and a Trijicon 3.5 MOA (adjustable brightness) RMR optical combat gunsight. The sight mount - which can be a nuisance to install - has been expertly inletted into the rear of the slide!
(He could have bought 3 Glocks for what he paid for this outstanding 3rd generation G-19! I left his place about 3 hours ago; and I'm still, 'green with envy'.)

According to many of the people on Glock Talk, the replacement #30274 ejectors, and the new (MIM?) extractors haven't solved all of the problems with Gen4 G-19's. (Neither has the new 0-4-3 RSA.) These replacement parts have only solved feeding and ejection problems in SOME Glock pistols. Anyone who doesn't believe this is welcome to perform the following search. Type this query into your Google text box:
"site:GlockTalk.com G19, Ejection Problems, Gen 4" (Drop the quote marks - OK!)
Here's some interesting outside reading for you: