I recently bought one and started driving it in January (´87 1.5L carbureted with 260k on it). Some rough back of the napkin calculations gives me approximately 25 to 31 MPG (7.4 to 9.4L/100km). Mine is probably a more worse case scenario because I have not done a tune up on it yet (excluding changing the oil of course) and I drive a lot of short trips (5 to 10 minutes) in cold weather (Canada not being the warmest of countries

) so I need to use the manual choke quite a bit. Not to mention the fact I´m migrating from a Trans Am that quit in January so my driving habits could use some improvements for fuel efficiency

... not that a base CRX can be driven like a sports car ...
The seats aren´t too bad as far as economy cars go, at least on short tips, but I´m considering putting the seats out of my other car into it (anyone tried this type of project - suggestions?). The handling is not to bad considering it´s a front wheel drive car, but in the snow it can be somewhat interesting to drive, although managable once you get used to FWD characteristics. The turning radius is one of the great things about these cars, not to mention the parking spaces it can fit into - you can turn within a (wide) two lane road without using the shoulders!
The road/wind noise at high speeds is quite a bit more noticeable than much newer cars too, although no complaints here as I´m used to a V8 with headers and sidepipes... The drive comfort is again, like an economy car, you can feel all the imperfections in the road but again not much different than a (older) sports car (minus the handing of course).
As far as reliability, mine is a 20 year old car with fairly high mileage (although my brother has an ´85 with 330k and is still going strong) so you can´t expect (most) new car reliability. They are a good car compared to many of this vintage though, and the nice thing about them is their simplicity - I was able to drive around for a couple weeks without an accessory belt when my alternator seized up because that IS the only accessory

. Mine is also carbureted so the fuel injection complexity is not there, but you do lose fuel efficiency with that. Also with old cars the availability of parts can be a problem, especially with cars this rare. For example the fuel tank is no longer available for the carbureted models (perhaps the fuel leaking from my tank doesn´t help my efficiency numbers either

) but I´m soon going to get it relined unless I find a good parts car before then - once I get the TA back up and running so I have something to drive...
But if you are used to driving old cars and do the maintenance yourself, the CRX will probably be quite reliable and cost effective to run.
As far as longevity, pretty near any car can be made to run for much longer than the current average life - I don´t think I´ve ever had a daily driver vehicle that was newer than 15 years old. But there comes a point when the time/effort/money being put into it is more than the cost of buying a newer vehicle. If you do the maintenance yourself, obviously that point comes a lot later in the life of the car, particularly if like me, you enjoy working on them. And even the problem of most of the rarer parts (not consumeables) can be solved with the purchase of a parts car - the parts you will scrounge off of them will more than pay for it...
I guess in summary, the CRX is hard to beat for cost of operation because the purchase price is so low (about 650 USD for mine), the fuel economy, and driving enjoyment, as well as reliability - that´s why I chose it. The small three cylinders like the Firefly, sprint, swifts, are more economical to run but are more of a tin box feel and driving characteristics (not to mention any last remnants of a ´macho´ feel

)
If you´re looking at Hondas though, don´t forget the early ´90s civic hatchbacks - I believe about the ´92/´93 to ´95s. They have VTEC engines that have better fuel economy before the horsepower started going up more, but the initial purchase price will set you back more..
Anyways hope this helps and good luck in your vehicle hunting - and of course, don´t forget about that bicycle either...

Man will occasionally stumble over the truth, but most of the time he will pick himself up and continue on. -- Winston Churchill