Talking specifically about the military hardware (I am not sure what they thought of the food, locomotives, and whatever else got sent over)...

It varied. The word "Studebaker" entered into the Russian lexicon as the trucks were so well regarded. On the other hand, the M3 Medium tank was "The Grave for Seven Brothers", as in comparison to the Soviet's own T-34, it really had... limitations.

The Archive Awareness website is an excellent source of information as to how the Soviets viewed Western equipment. For example, under "Churchill", ( http://tankarchives.blogspot.com/2013/05/lend-lease-impressions-churchill.html ) the Soviets concluded "The English heavy tank MkIV "Churchill" has sufficient armament, protection, and maneuverability to be capable of fighting German tanks effectively. Currently, the MkIV is an unfinished and unpolished design. When used in the army, the MkIV will require frequent repairs and replacement of parts and components. Several elements of the tank (turning mechanism in the same assembly as the gearbox, etc) are original, and can be recommended for use in domestic vehicles.""

Valentine tanks were well regarded mechanically, but they wanted to know why the British made such a great mechanical tank, and then put a pathetic gun into it.

The M3, as mentioned, was not considered particularly well. The M4, however, was a slightly different kettle of fish, and unfortunately, propoganda efforts have kindof diminished the view of the things in the former USSR nations. You will see opinions like "Good tank for peacetime, not for war" or "Un-necessary luxury. Our T-34 was more efficient." On the other hand, I've not encountered many actual assessments from the users saying that they particularly disliked it. The most famous operator in the English sphere is Dmitry Loza, who wrote "Commanding the Red Army's Sherman Tanks." He liked them, a lot. However, it is to be borne in mind that the Soviets and Americans had different issues to worry about. American tanks were built for the American industrial system, with perfectly machined interchangeable parts and reasonable ground. Soviet tanks were built to match Russian capabilities, and operated on god-awful mud in temperatures that no American tank was likely to need to operate in. As a result, it would not be out of place for the Soviets to think the lend-lease equipment was deficient in some sectors that they think important, such as track width. (In fairness, the US wasn't as happy with track width either, and eventually fixed it under a lesser priority, but that's another matter).

Then again, on occasion, that actually worked out in the American equipments' benefit. Take the case of the P-39 fighter. Not exactly a resounding success in US service, a number of Soviet aces did very well in it, because of the conditions of the Russian Front: In the Pacific and in Western Europe, combat tended to happen at high altitudes, where P-39 was disappointing. On the Russian Front, however, combat was at the ground tactical level, so everyone was flying around at low altitude, where P-39 worked quite well, thank you very much. As to the C-47 (DC-3), the Russians like it enough that they built it themselves, under the designation "Li-2"

Hurricanes seemed to be more 'accepted' than 'liked' (Better than nothing), but Spitfires seem to be more problematic to quantify. Apparently they weren't fond of the narrow track of the wheels, operating from rough airfields, this resulted in a high accident rate, and they tended to be very finicky about maintenance. Spitfire units tended to not last long on the front lines before being sent to rear guard operations. They liked the IX though, as a high-altitude interceptor. Spits thus were more successful in PVO (Air Defense Organisation) than VVS (Frontal Aviation)

Jeeps, trucks, radios etc. All were well received. Not glamorous, but critical.