TL;DNR: Sounds better than expected (genuinely good), V7-like, small/light, comfortable, fun, beautiful. Enjoying it a lot so far. Unless you're in to way too much detail on the U5, you should prolly stop here lol.
So a few additional thoughts, to accompany the photos. It's light. Haven't taken it to the bathroom scale But I am guessing 7 pounds. Satin neck and rolled edges typical of 2nd gen, nice. I can find no flaws in the finish and the 2 pc flame top looks really good IMO (grains in top could match just a little better but it doesn't bother me at all. Nit-picking there. The gloss finish is very shiny and looks great. Smaller size knobs, feel and look good. It's also very thin front-to-back. The small jazz body is indeed smaller by not by a lot so it does not feel small and has the dynamic and feel of a jazz body that you'd expect. The neck is very comfortable to get around.
The tone-- I may try to put up a clip later -- is IMO quite good; at least, I find it satisfies MY tonal goals, differing styles etc not withstanding. Maple board gives it some good snap and crispness unless you dial that out in the tone knob. I am judging this from zero gigs so far and using my "go-to" tiny rig home amp/cab for practicing and generally screwing around: Trace Elliot ELF and Barefaced One10 cabinet as I've played many basses through it and have a good comparative basis. Initially, I had pulled out an amp I don't use much at all (Aguilar TH350) with a cab I don't use (Aguilar SL12). I didn't find it pleasing - but that was the amp which I've never quite got the knack for tuning.
Bottom line there is simply that your gear determines a lot-- seems that this bass will permit you to get a good sound from a rig you like, and using my common reference set-up it was more or less plug and play. Bridge pickup seems to have more juice than some other PJ's (such as Fender Mustang 32" scale) so there's decent balance between the pickups, just like on a V7 etc. Passive only but was able to get decent level and tone with the simple VVT controls. Nice clean and crisp high end (D and G) but a whirl of the tone knob and you can take that ot if that's not your thing.
Short scale basses -and disclaimer, not a short scale guy generally- have lower string tension which can leave a little flub in the E string. Properly dialed I found the E string to sound pretty good; plenty of solid warmness (as lower tension and give) but still pretty well-defined and tight. Not as tight obviously as a34" scale E, but that is the nature of short vs long scale, rather than anything about THIS bass.
So I am enjoying the ease of play with the shorter scale while feeling I am not sacrificing much if anything in tonal quality. One can get good articulation out of the notes. Runs and soloing options increase, it's all right under your fingers without any reaching. Short scalers already know this obviously. I lowered the strings to taste and am so far impressed that the setup otherwise is decent-- getting no buzz as I lower it to a comfortable position. So, kudos Sire setup people ( I am sure the quality varies). I also injured my left index finger somewhat severely in January and still have a little ligament pain/stiffness on occasion (especially if not warmed up) so having a short scale to play at home and at (eventually) more gigs (the 4 or 5 I've had since C19, w/o this bass, outside only) is welcome.
The bass is smallish without seeming tiny, fits in the lap, great for couch or chair playing in that regard. I can totally see playing hours at a stretch at home, so light, thin, small. Neck looks wider but only by comparison-- standard width. I am looking forward to taking my micro rig modality (new word in everyone's mouth thanks to C19) farther with it-- 1.6 pound ELF, 15 pound One10, and 7 pound 30" scale bass that'll take a shorter case and would fit better for travel.
For context - I am, historically, fond of the Sires though I have more than 10 basses ranging from cheap to very expensive. From the Sire family I have a V7, V7 fiver - (maple board), and M7. Like them all but most attracted to the jazz bass. If you like the tone of the Sire V7's with a maple board, I think you'd like the tone of this bass quite well. Obviously, no fancy MM preamp, but this bass can produce a variety of tones and you can do more adjusting/fiddling at the amp to cover anything you can't dial on the VVT bass. It has tones similar to the V7's.
So, I am trying to find the negatives as everything has a negative side. In terms of the quality of the instrument it meets or exceeds my expectations. Drawbacks? It IS a short scale; the tonal quality and fell under the fingers of lower tension short strings vs higher tension long strings is a thing- a little fatter and maybe slightly less tight, but you can also bend notes easier.
In short, I guess, if you like short scale basses, I think you'd like this very much. If you like the Sire V7 tone especially of maple board versions, you'll like this. If you want a QUALITY home leave-it-out-at-all-times or travel bass, you will like this. I do look forward to gigging it at some point and seeing how it works there. I suppose if there's any negative to me, it's that I paid $399 for my first V7, but $499 for this smaller bass with less whizbang in it. Of course $399 V7's are a thing of the past so that's not a fair comparison. Overall very impressed, seems to make me want to keep playing it, and pick it up often. It's fun to play. It's beautiful. Let's see if I still like it so much in a few weeks.
This U5, I am told, is the most pre-ordered bass in Sire's short history, so I can't be the only person here who recently got one. I look forward to to other impressions, thoughts, issues, etc. So, this is my 2 cents, I have been anticipating this bass for a while; maybe it helps someone else who is contemplating it. Maybe I just bloviate. Maybe both.
Afterthought: No big thing but I really like the Sire logo on the headstock-- silver from one light angle and dark from another. hence the 2 headstock photos. I don't know if the 2nd gen basses have had that already, but I dig it.
