This is about the whole series, not these first chapters
Up until now my favorite manga series ;)
I reckon it could have been better, but it excels in several fields where others just do ok.
Urusei Yatsura was a pioneer in its time and had a great reception in Japan and also, for Rumiko surprise, outside (but of course way less than Japan). This was her first manga and she never expected it to be such a success (actually it started as a sci fi-comedy manga). So her first work catapulted her to fame and money, but she didn't stop there, her other works were mostly highly appreciated too (but I only recommend Ranma).
If you are familiar with manga and anime from now a days you may find this kinda plagued with cliches, typical characters or situations; but they most of them were not when this went out, Rumiko Takahashi popularity made them cliche, and the ones which were already there are pretty well used
Well enough, what this is about? the idea is to have a bunch of eccentric characters driven by normal desires perform lots of eccentric comedy, which is why some people found it kind of repetitive sometimes, also don't expect much about the main plot and all (that's just an excuse to dive in it).
My recommendation is don't read much at once, do it calmly (like for 30m when you just got home after work) so it doesn't become repetitive and you can really enjoy it
I think her success comes from her skill to create lots of amazing characters and situations and with all their rarities don't feel out of place. Also an interesting use of japanese mythology and folklore
btw I liked it more as it was going on, adding characters and all, the start and end are kind of weak. For example I really love it when it reaches volume 15 and we get to know Ryuunosuke. This is in part because Rumiko's manga was evolving a lot then
The main characters are Ataru (a lecherous guy always hungry for babies) and Lum (an obstinate et girl with the bad temper of Zeus), but they are just a part of the lot of characters after all. I particulary love Ran-chan, but there lots of great characters like Ataru in lecherus mode, the monk, kotatsu neko, the bird girl, Ryuunosuke (the girl_he-is-a-boy) and her father, Mendo and his sister (this one is really great sometimes), the eating baseball's balls guy and his sister... and well a lot more. Man it has been only a couple of months since I read it and I am nostalgic already