Truth be told, I have the same issues with my desktop PC, my laptop, my tablet(s) and my smart phone. But anyway here's what I like and don't like about Chromecast.

1st of all, forget all the things that it can do that a ROKU also can do. ROKU WINS! I really don't want to have to run an app from my phone, laptop or tablet first to push that content to the TV. Chromecast makes you do that. My ROKU comes with a remote that works with the TV and gives me access to all the same content (basically). Here's where ROKU falls short and why I still have Chromecast connected to my TV.

ANY content I have on my browser or for that matter my screen I can cast to my TV (Chrome TABS or entire PC Screens). I do a LOT of training and Chromecast is great for putting my computer screen up on the big screen for clients to view. You see everything that is in a particular TAB of the Chrome browser. I can show my clients very easily on any TV connected to Chromecast what I'm seeing on my screen. (Full HD recommended). So, chalk one up to a great office device for training and frankly for showing anything that you can browse to.

TIP: You can choose in Google Chrome Cast options to cast a specific tab in your browser or the entire screen. For training purposes, it's helpful to cast the entire screen because you can see the mouse move around the screen. Casting a Tab will let your browser act more like a remote, sending the tabbed content to the screen but not sending the mouse cursor or screen controls (or any other tabs you happen to open). In a similar vein, the new Chromecast Android app will let you mirror your Android device onto your TV (and it will switch to full screen if you go rotate your phone to horizontal. I use it for the same training purposes. I can show a client his website in responsive mode without too much difficulty and without everyone in the room having to dig out their smart phones.

ONE POINT HERE: ROKU does support screen casting on their streaming stick and the ROKU 3. It's new. It's in beta and it might be a Chromecast killer but somehow I doubt it. Google will find other Chromecast specific apps that will keep it a viable and fun product. APPLE TV can also mirror Apple devices although I wasn't as impressed as with what the Chromecast does in the same situation.

STREAMING VIDEO. ROKU vs. Smart TV vs. Chromecast

Anything you can stream to your PC, you can stream to your TV. However, don't expect to be bowled over by the quality of Chromecast in this arena. I've had better experience using the Smart-TV built in media center accessing a network drive (for movies I've backed up to MP4) than trying to cast those same movies from the PC through Chromecast. ROKU also does a decent job via one of the ROKU apps (ROKU Media Player) at finding content on my local network to stream to the TV. It just seems to work better than Chromecast at the moment. The streaming apps that do work well on Chromecast are the ones you'd expect: Netflix, Google Play, Epix, and others. Notably, Amazon is missing from the Google Chromecast apps selections. I think it will be a long time before this product competes with the defactor standard of streaming devices: ROKU.

So what would I recommend? For home use: ROKU can't be beat. It has a bazillion apps and is a very seasoned product. I would also recommend that you forget the Smart TV and just by a dumb TV and add the ROKU. You can save hundreds and the experience probably better than what your Smart TV has to offer vs. ROKU...just my two cents. I just bought a Sharp 50" at Best Buy for $350! Picture-wise it's the best TV in the house! As far as prices for Smart TV's go, a good buy for screens up to 55" is about $10/inch. So, if you look around, you should be able to get a 55" Smart TV for $550. You'll save $100 or more for a non-smart TV and you can just plug in a ROKU (or Chromecast).

So in summary:

Streaming TV services: Use ROKU or your Smart TV features. Chromecast works but you'll need to be operating your phone or PC as a remote. That cool factor lasted about five minutes for me.

Projecting, presenting or screen Mirroring: PC or Android: use Chromecast. Apple products: use Apple TV

Network streaming: If you're streaming your backed up DVD's from a home hard drive, I lead toward the ROKU media players. Your smart TV might have a good media player too, so try it (mine sucks).