The I SP is a very simple jet. We usually see 335 KTAS, fuel burn is 1200, 950, 900. 3 hours is about all you can do with any kind of reserve fuel left. Normally fly in the low 30's, but it can go higher (certified to 410) if you are light and it's cool out, but your TAS suffers above 350 and it takes awhile to get there. We usually can't make it back to Atlanta from Teterboro in the winter.
One of the problems with the I SP fleet is the wide range of aircraft conditions. The "latest" I SP's are still 25 years old. Many haven't been taken care of like they should over the years (parked outside, owner-flown, bare-bones maintenance, etc.), but there are some really nice ones in the mix also. There are some cheaper ones available, but you'll pay on the back end to bring them up to snuff. If you are paying less than 1 million for one, then it probably needs a little work. I've noticed many I SP's that are not RVSM'ed, either because the owner/operators don't fly long enough trips to see the benefits or because they feel it wouldn't pay off to go higher than FL280.
Our I SP has the Sierra 3-place rear seat which removes the aft half-bulkheads and places the new seat further aft than the original seats. This give TONS of room between the people seated in that seat and the rear-facing seats. It moves the potty to the side-facing seat behind the cockpit with removable curtains (Lear-style). This gives it 8 passenger seats when flown single-pilot, although it is a tight fit and they have to be light passengers or kids.
Reliability-wise, it is pretty darn good. Generator Control Units act up occasionally, but they prove fairly easy to fix. JT-15D-1A engines are about as bulletproof as turbine engines go. Most aren't on any type of engine program. One thing I and most people DO NOT LIKE is that the hydraulic system uses SKYDROL which will eat through any paint on the plane or floor of a hangar. Like all the 500 series Citations, windshields can bite you and when the airplanes approach 10,000 hours and over, the values tend to drop off in a hurry. It is a good airplane, but it isn't built like a tank.
According to the numbers, T/R's add 90K to the value We wanted one WITHOUT them since we fly most trips out of longer runways (5000'+) and by the time you flare, touchdown, and deploy them, it's almost 60 knots and bring it to idle, although the ability to go to zero-thrust is nice. We do have antiskid, which many do not have. We use 4500' wet and 3500' dry as minimum runway lengths.
Cost/NM is not the I SP's strong suit since you have a jet fuel burn but are only going 335 knots, but your acquisition price is much lower than anything comparable.
It can cary more than a CJ - we have a full-fuel payload of 600 lbs. Our's has a ZFW of 8400, but there is a SB that ups it to 9500 that involves changing airspeed indicators and limiting Vmo to 262 knots across the board. CG is almost never a problem except flying single-pilot where we have to have 30 lbs in the nose!
The plane is easy to fly, but it can be a little heavy on the controls at slow speeds like most 500-series Citations. It is easier and more responsive than the larger Citations, however, due to it's smaller size and moments.
At the end of the day, there are faster planes out there and cheaper ones to operate, but the I SP is just a good ole' airplane for the money. Easy to work on, easy to fly single pilot, and about as reliable as a jet can be.
ATC - "N800BF, did some one assign you 250 knots?"
As with any airplane that age, many have different mods done to them. Most coming from Sierra. Go to their website and read about the different ones. Some you may want to look for in a 501. Depending on your mission and pax load the sierra fuel mod is great addition.