i would say limited.
you must use digital servos. its set to 5.5ms timing (communications with the Rx) and anything under 18ms can/will fry analog servos.
its also somewhat limited on setup and adjustments.
lastly i know ALOT of folks (i was included) that had glitching issues with Spekys on Gassers, and lastly, if you want to use a remote kill switch, you have to get one designed to work with the Speky.
for a similar cost, you can get an Airtronics, FXHS3 2.4 system. or bettery yet and a bit more ( 180ish usd) you can get the Futaba 3PKS 2.4 or 3PMS 2.4.
afraid I have to totaly disagree (I have a DX3s)!!!
Don't have to use digital Servos with the DX3S. I have analogue HiTecs and no glitching issues at all.
Setup and adjustment wise, you have endpoint, expo, throttle punch, brake rate, steering rate. So I wouldn't say it is limited, it's not a £200 race Tx, but it's more than enough for bashing.
The range is fine whilst the Tx batteries are above 4.8v (good for at least 100m, after that I loose sight, get scared and stop), below that the range drops to about 30m. The Tx has a low battery alarm which you can configure to avoid this. So far I have not experienced any range issues.
The 5.5s is the packet timing between the Tx and Rx only, which is intentionaly above servo frame rate because the communication is digital. The data needs to get to the Rx faster than you need it in order to filter out any interference (this is the principal behind all 2.4Ghz systems, and it's why you get less interference with 2.4GHz than FM. PM me if you want the "science bit").
The Rx communicates with the servo at 11ms or 16.5ms (option in the menu on the Tx).
The killswitch is only an issue if you want to use the third channel for something else (like extra steering servo, or lights). This is because spekky Rx have inbuilt failsafe on all channels, which over-rides most kill switches, so the killswitch needs to work off the channel position (most switches work off "is the sichannel signal good"). However, a cheap and cheerful picoswitch works in all eventualities. KillerBee do a spekky kill switch, but this uses a 5s inactivity timer on the steering, which I personaly don't feel too comfy with.
The main issue I have had is that I wanted to run a 2nd brake servo, which I need to reverse for the correct linkage alignment. However you can only mix steering to the third channel (or use the auxilary switch) so I was a bit stuffed. I've ended up upgrading my throttle servo to a 20kgcm one and running all brakes and throttle from this.
On the Telemetry front, you don't need it on a gasser. I have the temp sensor installed on mine, but it is only useful to ensure I don't kill the engine from overheating (which is only an issue if the head gets stuffed with grass). Eventualy I'll install the RPM sensor for speed, but that's only for the sake of teh gadget, it isn't of any real use.
However, all said, I think Timmahhs' conclusion is correct, there are other radios out there which you should strongly consider before falling for the 'shiny' inbuilt telemetry (like I did since I had a nitro at the time, and telemetry is very useful on them). If I broke the DX3S, I'd probably consider a Futaba or Airtronics. Either way, 2.4Ghz is the way to go if you can afford it.