Onkyo offers a lot of product for the money, but they work in a similar fashion to what Samsung often does. They go "MORE MORE MORE!!!" but they never sit down and ensure that the pieces they are using in their product are fully developed and tested to ensure long reliability and build quality.
So, I have heard, and seen, higher levels of failure from Onkyo and Integra products than about any other manufacturer. They have more issues with HDCP than some other manufacturers, and their receivers are known to run hot. This doesn't mean that they will fail, but it means that they are more susceptable to heat related failures than other product out there.
I've also personally had issue with Onkyo where they've shipped product they knew was buggy, and when I actually called them up about how to fix it, they said they were not going to fix it in the current model. So, a feature which was advertised was not actually usable and they didn't care enough to either remove the advertising, let consumers know, or come up with a fix.
Now, it doesn't mean that their product will fail, but I would expect there are some very satisfied Yugo owners as well. I'm just not about to recommend that someone spend their hard earned cash on a brand which has shown they don't have a higher level of engineering quality in their product.
On the flip side, Denon typically doesn't come with a bunch of extras for the money, but their stuff typically just works. They focus on the A/V receiver portion first, ensure high quality components go into the box, and test their product thoroughly. The amplifier section is well regarded for it's robustness, and they offer features such as bypass modes which shut down non-essential portions of the receiver to cut down on noise going into the system.
I don't HATE Onkyo, but they aren't my first recommendation. At the entry level, I think they offer some of the most bang-for-the-buck product available and it works sufficiently well for most people, and doesn't have enough bugs to really cause headaches for most.