I have been playing around with Rocketroute for use in generating IFR routes, doing briefings, filing FPs etc. It seems to work well, is quite user friendly and has a mobile app for use when away. I would be interested in views on other packages out there for IFR (EuroFPL etc) and relative merits of each package.
Note, I am not focussed on navigation but planning and pre-flight.
For flight plans: AeroPlus FlightPlan in the Appstore. Also generates and validates eurocontrol IFR routes. You only have to give the departure and destination and a correct FL. The app will suggest a few routes for you.
Speaking of IFR (Eurocontrol) route planning, the only tools I know (for GA) which generate an "intelligent" route are
Both the above also give you access to the Eurocontrol "route suggest" feature. In fact FPP does that anyway and offers you that if the result is better than its own. (RR may do that too). This feature often produces a poor result if used as the only method, not least because the whole route is generated at a single level, which for the lower airways (below FL200) is a poor strategy.
The other popular flight plan filing service, EuroFPL, offers just the "route suggest" feature.
Personally, I use EuroFPL, and have done so for ages. I just use it to file flight plans. I also use Afpex as a backup. One always needs two ways of doing anything 
There are numerous ways of doing the same job, and if you got 20 IR holders (who actually fly anywhere) you would find they use 20 different methods This is unsuprising given there is almost zero "operational" training in the JAA IR, and the FAA IR doesn't go into the weird ways they do things in Euroland.
I fly with everything printed, so no backups are needed. There are numerous ways to generate printed stuff. One could get it out of FPP alone; you just need a simple plog and an IFR enroute strip chart printed on A4 sheets (or similar). I paste the ex-FPP route into Flitestar and it plots it and then I print the strip charts from that (you get quite nice enroute charts then). I have not flown with the real printed enroute charts (Aerad or Jepp) for years.
Alternatively, one could print whatever off to PDFs and "somehow" transfer it to say an Ipad and then view it on that (Goodreader etc). It works, plenty of people do it, and I have used that in emergencies (I used to carry a little printer on long trips but don't anymore because one really needs it in the hotel) but I don't like it because if the Ipad packs up then you have to improvise big-time.
I think RocketRoute is by far the best package out there and it's priced reasonably. The way they serve the Eurocontrol approach plates is very convenient (web download + iPad app). The flight log it generates is good, too. Filing flight plans and keeping track of them (e.g. delaying) works very well, never had any issues.
I've tried the other products mentioned but I think RocketRoute delivers exactly what I need and I have very little reason to complain.
We use RocketRoute for IFR and have no problems. We seldom file above FL080 so the single level is not a major problem
Sometimes it matters, sometimes not.
In France, you have the fairly uniform Class E in which Eurocontrol routes work ~FL070 to FL110.
Above that you have the fairly uniform Class D in which Eurocontrol routes work FL120 to FL190.
For IFR, the two combine, into a single airspace in which almost all "obvious" (i.e. straight off the ones shown on the 1:1M SIA chart) routes "just work", FL070-FL190.
There is no advantage in filing say FL140 over say FL070 - except for operational reasons e.g.
)France also has very few unidirectional airways (a stupid idea all over Europe, which ATC mostly ignore but it screws around with route planning).
But no other country in Europe (AFAIK) is that easy. Maybe Germany is? I have never filed IFR at low levels there - normally FL120+. In most places you have to hack it a bit. Usually one gets much better routes at FL120+ (near Frankfurt e.g.) and sometimes one can avoid stuff by going below say FL090 (which ATC invariably ignore and let you stay at say FL140 ).
So in using rocketroute, should I really care about the specific route or just focus on altitude and a reasonable route, get airborne and sort it out?
You have to file the Eurocontrol-validated route, and be prepared to fly it at the filed level.
Let's say you filed for FL140.
Once airborne, if say it's a nice day then why not ask ATC for a "stop climb" at FL100. The oxygen flow rate is then very low (or zero if you are a real man 
) and there can be performance / economy benefits.
ATC will normally let you unless there is "stuff" which affects you at that level but which would not affect you at FL140. This does happen e.g. military activity. Or busy TMAs, etc. The result is they route you around it, or tell you that unless you do climb you will have to go around it, etc.
If OTOH you see muck ahead with FL160 tops, ask ATC to climb to FL180, or whatever. ATC will always let you, IME.
Rocketroute, or whatever tool you used to generate the route, is nothing to do with any of this.
I understand that RR has nothing to do when in the air but alt and route can essentially be played with once airborne.
Once airborne, if say it's a nice day then why not ask ATC for a "stop climb" at FL100. The oxygen flow rate is then very low (or zero if you are a real man ) and there can be performance / economy benefits.
Ummm, real men have pressurisation...
So in using rocketroute, should I really care about the specific route or just focus on altitude and a reasonable route, get airborne and sort it out?
That is a good question. As Peter said, you have to be prepared to fly your filed route and you have to do your IFR fuel planning based on it.
I have tried both -- taking off with a completely insane Eurocontrol approved route with 40% overhead and doing the same with a perfect hand optimized route with a lot of DCTs and about 3% overhead. The actual result was the same in both cases, an almost direct flight.
Fact is that in lower airspace, there is not much going on in Europe outside of terminal areas. My typical experience for IFR flights within Germany is "cleared direct destination" once airborne, unless there is a terminal area in between.
But no other country in Europe (AFAIK) is that easy. Maybe Germany is? I have never filed IFR at low levels there - normally FL120+. In most places you have to hack it a bit. Usually one gets much better routes at FL120+ (near Frankfurt e.g.) and sometimes one can avoid stuff by going below say FL090 (which ATC invariably ignore and let you stay at say FL140 ).
Generally very easy, controlled airspace (E) starts at 2500ft AGL or lower and you can file whatever is above the minimum radar vectoring altitude (MRVA), often as low as FL040. If you want to make sure there won't be unknown VFR traffic, you file at least FL100 (airspace C). The only nasty place is the Frankfurt terminal area. Since putting the 4th runway into operation earlier this year, you can no longer file transits below FL140 which is very annoying. Every now and then you can request a transit lower than that but unfortunately that is still rare. There is hope that once the procedures with the 4th runway settle (or they introduce point merge), they will relax it again but for now the Frankfurt TMA is a dark spot for GA.
