Anything out there or rumored to be coming soon that is better than Roku?

Roku is pretty solid. I like mine. It helps to have relatives that have HBO/Cinemax/EPIX logins they don't use, but between netflix/amazon/hulu, it's pretty tough to beat.

Roku is very hard to beat.  We've had ours for a couple of years now and it just plain works.  While there are other boxes that will stream video I've not seen any get even close to the Roku's ability to buffer on slow\poor Internet connections.  We have what I call third-world connectivity.  My ISP uses a Motorola Canopy system to deliver service via RF (2.4 GHz).  It's way better than dial-up but not as good as cable or DSL which are unavailable to me.  My service hovers around 3 Mbps down and 0.75 up with high latency especially compared to cable or DSL.  The Roku box delivers consistently with my Internet connection.  I've tried other devices for example DVD\Blu-Ray players that also stream and they simply do not function on my connection. The Roku box just hums along.  Every once in awhile, if my Internet service is having a bad day, the Roku box will stop to buffer a bit more often but even on the worst of days once it sorts out the rate it will settle in and just deliver.  Keep in mind that in order to deliver when it has a poor or degrading Internet connection it is downgrading the quality level of audio\video but something is better than nothing.  We're not living at the high end of the A\V food chain anyway.  I've still got a tube TV! (If it ain't broke, don't fix it.)

Along the same line you can run a Roku box off a cell modem just fine.

I don't know if there is anything better on the horizon.  Roku sets the bar pretty high given the Internet infrastructure and A\V as we know it today.

A number of friends have them and love them as well.  You can't go wrong with a Roku.

Xbox 360 + Kinect + Netflix/hulu/Epix/Zune/FiOS/ESPN/Youtube/Xfinity/Vudu + streaming content from your local network = winning

With the Kinect there is no need for a remote, all the online streaming services are fully accessible through voice commands.

I have 4 streaming devices at home (WII, Xbox360 kinect, Roku, Samsung Bluray) and have installed just about everything that exists.

Xbox is really cool but tough for non gamers to figure out. Other then via kinect, you cannot use a universal remote with it.
Samsung Bluray has a really pretty front end and streams well but it constantly updates and locks up on occasion, needing to be unplugged and plugged back in to start working again. Bluray plays OK with universal remotes and has Iphone/Ipad and Android control apps available.
Wii is funky and not HD, need to use the factory controllers.
Roku has the prettiest, easiest to use frontend out of all of them I have. Easy to integrate and control, has Android and Ithingy support. Also pr0n available if you are into that sort of thing.
Appletv is pretty cool as well (being able to display ipod/ipad on a connected tv is awesome), but I gotta give it to Roku for overall ease of use, most available content and reliability.