Not a big beef with them, just certain things are lacking, chiefly that they tend to come out of the gate way more bug-laden than I think they should be, and patching tends to take the better part of several months or more, as you can see by the release histories. That said, to Cisco's credit, they do actually document and publish most of the issues, and eventually get to fixing a lot of them. It just feels to me like they treat the product too matter-of-fact-ly, compared to their other stuff. I guess I can't blame them when it comes to selling a $200 box, versus a $20,000 ISR, but still, I think they could do better there.
Additionally is the absence of some form of AQM for QoS, using modern qdiscs such as fq_codel or cake. You can dismiss bufferbloat at the edge as a bunch of woo woo considering other limitations at large, even somewhat avoidable via proper application of more legacy QoS protocols (many of which
are included on the RV's), but, still, I've seen good AQM make a massive impact on a many SMB networks, even those that had their switching fabric pretty well geared-up and configured, along the lines of what you've mentioned, and in some cases even beefier.
Much of the UX and workflow is quite clunky (ex. multi-WAN interface weighting options require duplication of the precedence numbers for any interfaces to which you want to apply precedence... yes it works, but certainly not intuitive by any means). I get that pedantic UI/UX interpretations are really secondary to functionality, but management, when it has to be done, is made all that much more of a pain, especially when compared to the updated UI's and CLI feature-parity of many of the other competing security products such as Fortigate, Sophos UTM, Juniper SRX (all of which can get pricier per box, I understand), hell even Mikrotik and Ubiquiti are often more of a joy to use in that regard, and that's saying something...
A last disappointment is perennial to Cisco and that's their licensing. Not a fault of the the RV34_ specifically, but the included AVC web filtering and AnyConnect SSL have both been subject to it, although Cisco just removed AnyConnect from the smart licensing umbrella as of the last firmware update to a default 50 users, after I would guess hearing from enough complaints. To their credit, again, at least they did something about it.
Overall, again, not a bad product, especially for <$300, it has its use-cases, and I'm probably being a bit harsh in places when compared to the alternatives, but it's certainly no silver bullet and is soundly beaten in several areas by others. Just have to know when it's best integrated.