There are extremes on both sides in this thread, and as usual, the truth is pretty much in the middle. The class isn't hopeless but playing as a combat sentinel, I feel like it is one of the weaker classes. I'm was 34 when I fought the harrower's or whatever their name was and while it was a green quest at that point, it was very difficult to complete. I wiped on the last harrower 3 times and was ready to pull my hair out.
also I don't need to "learn to play". I have 10 years of warcraft, 5 years of AO, 2 years of RoM, 2 years of CoH, and a few other random mmo's under my belt. I have everything keybound, have a razer naga, use my interupts, keep stims with me, and use medpacs. I have played BH and smug. to the mid 20's and they are infinitely easier than Sentinel.
TL; DR the class is due for a buff but nothing major. Just some tweaks to put it on par with the ranged classes.