One of my favorite combos right there. Though honestly what doesn't go well with weed?
With out a major tolerance (slight tolerance is ok imo), tramadol imo is the bees knees. It may have a low potency (which of course is proportional to its affinity and efficiency), but the effects profile is awesome imo (it may not be able to keep up with other common opioids in reduction of pain, but it doesn't have a broader scope of antinociceptive effects in comparison to your common opiates) . I could do with out the SNRI effects, but they do produce a nice slight mood lift. Tramadol also has action the NMDAr sites as an non-competitive antagonist (1), though, I can't comment on the influence of these effects, I do enjoy nmda-antagonism, and it is said that it does contribute to the alteration of perception to pain, as NMDAr's are said to deal with the perception of pain (possibly why tramadol has been shown to be effective in treating allodynia [pain response to stimuli not usually seen to induce such a response]). Ketamines analgesic response associated with NMDAr-antagonism isn't to far off either from tramadol (in terms of concentration values to induce inhibition leading to analgesic response). So in sum, I'd imagine the the NMDAr-antagonism does contribute to your perception of effects of the drug. I am curious as to whether the NMDAr-antagonism prevents rapid opioid tolerance (I find it to raise a lot slower in comparison to the common opiates).
Anyway, I find the euphoria to be outstanding even in comparison to heroin or hydrocodone (both of which give me the best euphoric response). The long duration is also a plus, though is seen by most as a disadvantage for recreational use. You get 8 hours of a high rather than 2-6 hours with the oxycodone, hydrocodone, and heroin (of course this range is encompassing all three drugs durations together). Also the stimulation cause by I believe the SNRI activity is quite interesting. You can stand up (even when just nodding before or getting close to nodding) and suddenly feel energized to accomplish something (I've gone to class at doses +300mg and would drift into the opioid zone if I was just chilling, but I could manage to focus when I need to do work).
The downsides I see are from the 2 hours comeup, increase risk for seizures and the low potency with a ceiling effect similar to codeine.
As a rec opioid user my tolerance hasn't gotten to high to diminish tramadols response in me (in average of 3-4 times a month, but this average doesn't take in account the lack of access for portions of the year). I can understand how a regular user can get next to nill with safe doses.
(1) - Both tramadol and M1 metabolite, at concentrations from 0.1 to 100 μM, suppressed the NMDA receptors, with IC50 values of 16.4 and 16.5 μM (10 μM is sufficient enough to inhibit the NMDAr). [though these findings are not in humans, but rather Xenopus oocytes.] {http://www.anesthesia-analgesia.org/content/100/5/1400.full}
It's been lingering on and on and traveling yesterday made it worse again. 
Not bad!
Santa was very kind, thanks for asking! He gave me some cool stuff for my hi-fi stereo soundsystem. 
And some great reading material, which I'll have to find the time to indulge.
