I never watched or knew anything of the Who-universe pre-reboot, but I've generally enjoyed the new series immensely.
That said, I do agree that the Daleks (and Cybermen) seem to have been cheapened as the villains that people talk about them being in past series. The trouble is with the pacing of Who, generally - unlike other recent series, Dr. Who has retained much of the episodic-everything-turns-out-all-right-at-the-end-of-the-episode that TV series always had in the past, with the exception of 2 and 3 part episodes.
We know from the beginning that even if the Daleks show up, the Doctor is going to best them one way or another. We also know that this race that terrified the Doctor in the past was supposedly wiped out in a major sacrifice, but then they keep reappearing here and there with enough frequency that a Dalek showing up is merely ho-hum and lacks dramatic impact. Moreover, everytime they show up in greater numbers and the Doctor bests them AGAIN, so we start to wonder what all the fuss was about and aren't these tin cans amusing? The cybermen suffer this fate even more.
Compare that to the terror inspired by the Weeping Angels. There's an enemy the Doctor literally cannot beat, or reason with, but rather basically has to run from constantly because they are truly unstoppable by their very nature. Even they have been cheapened somewhat recently, but they still retain much of the terror at their introduction.
Nuke makes an excellent point - the Daleks have suffered much the same fate as the Borg in the Star Trek universe. When the Borg were first introduced, they were essentially invincible (only Q rescued the Enterprise). The next time they showed up, they beat the **** out of the Federation and basically everyone else - their defeat was by the smallest of margins. After that, they got much less terrifying until, by Voyager, they were basically just as fallible as everyone else and not all that difficult to fight.
As it stands, the Daleks need a serious overhaul to be a true villain.
Also, I am noticing more and more that Doctor Who is getting JJAbrams-Lost Syndrome, and introducing mysteries at a pace much faster than the old ones are resolved, to the point where they forget about past issues and just carry on leaving gaping holes in their wake. People remember three things very well; most people can remember up to seven things reasonably well; beyond seven, facts get lost. Writers of TV series that are shrouded in mystery would do well to remember that.